Add movement artist filter modal and fix large-hall texture blanks

Clicking a movement opens ArtistFilterModal to choose artists before the gallery. Large halls no longer permanently blank frames when texture loads exceed the overlay deadline; fall back thumb to full to on-demand API.

Co-authored-by: Cursor <cursoragent@cursor.com>

Documentation/basics.md

@@ -8,7 +8,7 @@ The app is organised as a **drill-down hierarchy**:
 
 1. **Timeline** — historical eras (Ancient → Contemporary) with definite or fuzzy date boundaries.
 2. **Movement flow** — art movements as curved SVG streams on the same year axis; documented predecessor→successor branches; portrait thumbnails placed along each stream.
-3. **3D gallery** — one personal hall per artist, a **movement gallery** (click a movement name), or a **guided tour** hall (timeline → **Tours**): period-themed or tour wings of up to ~55 works, U-shaped hang (left → end wall → right).
+3. **3D gallery** — one personal hall per artist, a **movement gallery** (click a movement name → artist filter → hall), or a **guided tour** hall (timeline → **Tours**): period-themed or tour wings of up to ~55 works, U-shaped hang (left → end wall → right).
 4. **Painting detail** — full work in the centre, *Influenced By* on the left, *Influenced* on the right (paintings, artists, or movements), optional **curator notes** and **art-history notes** with image markers, prev/next catalog browsing, optional fullscreen, link to artist biography.
 5. **Artist biography** — portrait, lifespan, movement, and Wikipedia-sourced intro text (`bio_short` / `bio_full`). With debug mode on, the same image-audit panel as painting detail (portrait search, **Checked** / **Fix it** / **More** / **Clear** / **Upload**).
 
@@ -209,9 +209,9 @@ Pan, zoom, and era/event click-to-zoom only update **local** `viewStart` / `view
 |--------|------|
 | Overlay **“Loading art history…”** | Until the first catalog fetch (`bounds` + `timeline` + `artists`) completes |
 | Bottom banner **“Loading portraits…”** | While artist portrait thumbnails are still downloading on the movement flow (timeline stays interactive) |
-| Overlay **“Opening artist/movement gallery…”** | Between clicking a portrait/movement and the 3D hall data being ready |
+| Overlay **“Opening artist/movement gallery…”** / **“Loading artists…”** | Between clicking a portrait/movement and the 3D hall (or artist-filter modal) data being ready |
 | Overlay **“Loading gallery…”** | While the 3D canvas initializes, HDR Environment settles, or door/hall shaders warm up after the hall opens (painting images continue loading after the overlay dismisses) |
-| Overlay **“Loading paintings…”** | While wall painting textures are still downloading / uploading to the GPU |
+| Overlay **“Loading paintings…”** | Brief counter while wall painting textures start downloading; large halls (e.g. Byzantine) keep loading after the overlay dismisses — a slow image no longer permanently blanks the frame |
 | Overlay **“Restoring gallery…”** | Briefly after WebGL context loss while the canvas remounts |
 
 View updates are **batched to one commit per animation frame** via `createViewChangeScheduler()` in `timelineView.ts` (`HomePage.tsx` → `handleViewChange`), so rapid scroll-wheel events do not flood React with separate renders.
@@ -272,7 +272,7 @@ Each artist appears as a **portrait circle** on their movement’s stream row:
 | Scroll wheel anywhere on flow canvas | Zoom (same year range as timeline; works over portraits and labels too) |
 | Drag on flow canvas | Pan |
 | Click portrait | Open artist biography |
-| Click **movement name** (label on stream) | Open **movement gallery** for that movement |
+| Click **movement name** (label on stream) | Open the **artist filter** modal for that movement, then the movement gallery |
 
 **Zoom/pan performance:** The movement canvas uses a **capture-phase** wheel listener so scroll zoom works even when the cursor is over a portrait. While scrolling or dragging, a short **interaction mode** (~120 ms after the last input) draws simplified solid SVG strokes and temporarily hides portrait/label DOM so zoom stays responsive; full stream styling and portraits return when you stop.
 
@@ -326,11 +326,11 @@ Predecessors and successors come from **`painting_influence_sources`** (painting
 
 ### Movement galleries
 
-Enter from the home page by clicking a **movement name** on the movement flow (`MovementBands.tsx` → `GET /api/movements/:id/gallery`).
+Enter from the home page by clicking a **movement name** on the movement flow. First a centered **artist filter** modal (`ArtistFilterModal.tsx`) loads `GET /api/movements/:id/artists-summary` (portrait, lifespan, painting count). All artists are selected by default; deselect any to exclude their works, then **Enter gallery**. The client loads `GET /api/movements/:id/gallery` and filters paintings to the selected artist IDs before opening `VirtualGallery`.
 
 | Rule | Implementation |
 |------|----------------|
-| One gallery per movement | All paintings by artists in that movement, sorted chronologically |
+| One gallery per movement | Paintings by **selected** artists in that movement, sorted chronologically |
 | Wings | Catalog split into wings of up to **55 works** (`movementHallLayout.ts`); large movements (e.g. Baroque) use multiple wings |
 | Paintings on walls | **Left, end, and right** — single-wing halls keep the far wall solid (full span); multi-wing halls hang end-wall works on panels beside the back exit |
 | Wall order | Same U-shaped hang as artist halls (left → end → right) |
@@ -373,9 +373,9 @@ Full guide: [tours.md](tours.md).
 
 ### Shared 3D behaviour
 
-**3D images** use locally cached files only (`galleryImageUrl` in `client/src/api/client.ts`). Remote fetches are too slow for realtime WebGL textures; the client calls `POST /api/artists/:id/preload-images` or `POST /api/movements/:id/preload-images` automatically when entering an **artist** or **movement** hall (public routes — link disk files and regenerate missing thumbs). While a texture is loading, the frame shows the canvas cover instead of a white placeholder.
+**3D images** prefer local thumbnail files (`galleryImageUrlCandidates` in `client/src/api/client.ts`: thumb → full → `GET /api/paintings/:id/image?size=thumb`). Remote Wikipedia fetches are too slow for realtime WebGL textures; the client calls `POST /api/artists/:id/preload-images` or `POST /api/movements/:id/preload-images` automatically when entering an **artist** or **movement** hall (public routes — link disk files and regenerate missing thumbs). While a texture is loading, the frame shows the canvas cover instead of a white placeholder. A per-image deadline only releases the boot overlay counter — it does **not** permanently blank the frame if the download finishes later (important for large halls such as Byzantine).
 
-**Boot overlay** (`VirtualGallery.tsx`): the center shows **“Loading gallery…”** until the WebGL canvas is ready, HDR `Environment` has settled (or timed out / failed), and a one-shot `gl.compileAsync` warm-up finishes so entrance doors / passages (often frustum-culled at spawn) do not hitch on the first turn. Painting textures keep loading in the background (prefer thumbnails; per-image timeouts; GPU upload after decode) so large halls (50+ works) are not stuck on the overlay. Env and shader warm-up also have short timeouts. The 3D hall stays mounted while painting detail or bio overlays are open; returning remounts the canvas when the hall becomes active again.
+**Boot overlay** (`VirtualGallery.tsx`): the center shows **“Loading gallery…”** until the WebGL canvas is ready, HDR `Environment` has settled (or timed out / failed), and a one-shot `gl.compileAsync` warm-up finishes so entrance doors / passages (often frustum-culled at spawn) do not hitch on the first turn. Painting textures keep loading in the background (prefer thumbnails; fallback to full / on-demand API; GPU upload after decode) so large halls (50+ works) are not stuck on the overlay. Env and shader warm-up also have short timeouts. The 3D hall stays mounted while painting detail or bio overlays are open; returning remounts the canvas when the hall becomes active again.
 
 **WebGL context-loss recovery:** on some GPUs/drivers (notably certain Chrome setups) the browser can drop the WebGL context right after entering a hall, which would otherwise leave a permanent dark window. `VirtualGallery.tsx` listens for `webglcontextlost` / `webglcontextrestored`, calls `preventDefault()` so the browser can restore the context, and remounts the `<Canvas>` with a fresh context (a **“Restoring gallery…”** overlay shows briefly). The network-loaded HDR `Environment` map is wrapped in an error boundary so, if it fails to load, the hall still renders without reflections instead of unmounting the whole scene.