feat(text): composite shared text rasters in output

Raster static text on UI-thread changes and reuse the same transparent BGRA frame in preview and all compositor paths. Cache text frame identity in the frame-pump signature and invalidate static bakes on edits. Follow OBS text-source conventions: https://obsproject.com/kb/text-sources

TASKS/task-03-capture-pipeline.md

@@ -5,7 +5,7 @@
 
 **Goal:** Real video preview in the center panel — the minimal source set below, composited per scene.
 
-### Status: 🔶 In progress — **Alerts (item 20) SHIPPED 2026-09-24 via TASK 43**; still open: item 17 (Text source), item 20's `RewardEvents` SQLite persistence half (16 compositing + 19 background removal excluded)
+### Status: 🔶 In progress — **Text source (item 17) SHIPPED 2026-11-04 via TASK 3·17; Alerts (item 20) SHIPPED 2026-09-24 via TASK 43**; still open: item 20's `RewardEvents` SQLite persistence half (16 compositing + 19 background removal excluded)
 
 1. ✅ **Milestone 1 — webcam** — MediaCapture (WinRT SDK projection) with device enumeration, CPU-first frame source, refcounted `CameraManager`, picker dialog, clip shapes (Traditional + Round) + mirror, 480×270 default placement — schema v2
 2. ✅ **Schema v3 (Ship Branch A)** — multi-scene webcam (singleton `Webcam` + per-scene `WebcamSceneConfig`), right-click border/context menu, static OBS-style borders, 50%-per-dimension webcam size cap, device-swap (`ReleaseAllAsync`) — 25 tests passing
@@ -23,7 +23,7 @@
 14. ✅ **Social bar v2 (six-slot dialog, sign-in gate, real logos)** — global bar layer (never a Source, no sources-list row), content-sized, centered, GREEN glow when ON, top/bottom snap-drag (default BOTTOM, persisted `SocialBarPosition`; drag clamps to 0/1040, tie→bottom). Footer Social button gets a state dot (green=ON). Dialog "Social Media Site Promotion" (`SocialsDialog` + `ViewModels/SocialsDialogViewModel`, WPF-free + injected `ISocialValidator`/sign-in/sign-out fakes): ON/OFF bar switch (`SocialsConfig.BarEnabled`, schema v8), 6 fixed slots — row 1 always YouTube (signed-in → channel handle; signed-out → sign-in gate → OAuth; delete → confirm sign-out, mirrors `StopStream`), row 2 free, rows 3-6 lock icons on freemium (Premium seam: all six). Validation: `DetectService` (URL domain / fediverse `@user@domain` / bare→Website) → async `ISocialValidator` on confirm/Save; valid snaps to text + real service logo (bundled SVG path data via `LogoDataFor`, Simple Icons CC0 — initials badges gone); invalid → red do-not, stays editable, Save blocked. LCR justify dropped (`BarJustify` unread), per-scene toggle dropped (`Scene.HasSocialBar` back-compat). **Post-test fixes (2026-08-12):** footer label "Socials" (not "Social"); fediverse `@user@domain` validates — the full handle is the identity end-to-end (`DetectService`/`CanonicalUrlFor`/`HttpSocialValidator` build `https://domain/@user`, no domain loss); **Cancel is a hard stop** — `ISocialValidator.LookupAsync` takes a `CancellationToken`, dialog VM owns a CTS, Cancel/X/Save abort in-flight lookups (HTTP request killed, canceled continuations never touch slot state), and `ConfirmEdit` skips re-submitting identical text (LostFocus on dismiss never re-fires a lookup). `HttpSocialValidator` now has real tests (fake `HttpMessageHandler`). 105 tests passing. **Post-test fixes (2026-08-12, round 2):** fediverse `@user@domain` no longer shows a generic chain — it resolves to the instance's actual software via nodeinfo (`/.well-known/nodeinfo` → `software.name`; `SocialService.Fediverse` enum member + `SocialEntry.FediverseSoftware` persisted in a new `SocialEntry.Software` column, schema migration by column-presence) and renders that software's bundled logo (`LogoDataForFediverse`: mastodon/peertube/pixelfed/misskey/lemmy/pleroma/firefish, generic fediverse honeycomb fallback). Dialog row-2 edit/trash icons were too dark — `IconButton` style gains `Foreground=#d0d0d0`; trash overrides `#e94560` (app red). 112 tests passing. **Post-test fixes (2026-08-12, round 3):** a fediverse handle whose identity domain is itself a redirect (e.g. YunoHost default-app subdomains — `@user@llamachile.tube` where the mastodon instance lives at `mastodon.llamachile.tube`) now still resolves its software: nodeinfo on the identity domain is SSO-blocked, so `HttpSocialValidator` follows the bare root `https://domain/` 302 to the real instance host and re-runs the nodeinfo lookup there.
 15. ✅ **Window capture** — absorbed into the Screen picker (no separate source type); dedicated window-as-source work is pending
 16. ❌ **Scene compositing (D3DImage/MediaElement)** — SUPERSEDED, permanently out (2026-09-01): the software output compositor (TASK 4 step 1) + the XAML preview ARE the design; a D3D11 swap stays a possibility behind the `VideoFrame` seam, not a feature
-17. ☐ **Text source** — live text ("Starting soon", "Back in 5", handle, callout)
+17. ✅ **Text source (TASK 3·17, 2026-11-04)** — independent static multiline text layers with per-layer font, size, color, emphasis, alignment, position and size; additive layout persistence; editor and preview share the cached raster with compositor output
 18. ✅ **Chat box** — YouTube live chat rendered *on* the stream so viewers read along in-video — `ChatBoxRenderer` (WPF FormattedText → VideoFrame), configurable font size/color/badges/timestamps/max-messages via Elements panel, schema v10, persisted across save/load
 19. ❌ **Background removal (milestone 2)** — ONNX Runtime + DirectML, MediaPipe Selfie Segmentation — deliberately NOT in this build
 20. ✅ **Alerts — Super Chat / membership pop-ins (SHIPPED 2026-09-24 via TASK 43, NATIVE)** —
@@ -126,5 +126,4 @@ Preview shows the transition too (WYSIWYG). No wipes/slides/LUTs beyond the four
 7. **Drag/drop placement & reorder** — intuitive, visual (per design principle):
    1. **Preview:** click-drag a source in the center panel to reposition it; resize via handles
    2. **Scenes list:** drag rows to reorder scenes
-   3. **Sources list:** drag rows to reorder sources (this *is* the z-order) — implemented
-
+    3. **Sources list:** drag rows to reorder sources (this *is* the z-order) — implemented