android(call): Increment 2c — screen-share + received-screen pinch-zoom

Screen-share (send): startScreenShare requests the MediaProjection grant via
startActivityForResult, then CallMedia.setScreenShareEnabled(true,
ScreenCaptureParams(data)) publishes it over the native LiveKit room.
stopScreenShare unpublishes. Both emit screenShareState so the web button
reflects reality (incl. a declined grant). LiveKit's SDK manifest already
provides the mediaProjection foreground service + FOREGROUND_SERVICE_MEDIA_
PROJECTION (merged into the app), so no manifest change is needed.

Received shared screen: implemented setTileZoom (was a no-op) — the web
captures pinch/pan under hole-punch and forwards {scale,tx,ty}; CallVideo
applies it as a renderer transform (scale about centre + translate ×density),
scale<=1 clears it. Mirrors the iOS applyZoom contract. Screen tiles already
render aspect-fit.

APK-only: the web bridge already calls these methods and received-screen
rendering is gated on ANDROID_NATIVE_VIDEO (already on) — no server/web change.
All LiveKit 2.29.2 APIs (setScreenShareEnabled, ScreenCaptureParams) verified
against source. Clarity-when-zoomed (adaptive-stream) is a follow-up if needed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

TECHSTACK.md

@@ -1,6 +1,6 @@
 # Tech Stack — BizGaze Connect
 
-> Living document. **Last updated: 2026-11-03** (rev 5). Update this file whenever a dependency, platform, service, or
+> Living document. **Last updated: 2026-11-03** (rev 6). Update this file whenever a dependency, platform, service, or
 > tool is added/removed/version-bumped. See [Maintaining this file](#maintaining-this-file) and the
 > [Changelog](#changelog) at the bottom.
 
@@ -111,7 +111,9 @@ hash, per-user salt, timing-safe compare), opaque random session tokens, SHA-256
     **audio** (Kotlin `CallMedia` + a `microphone` foreground service for background audio + `AudioSwitchHandler`
     routing), gated by the server flag `ANDROID_NATIVE_MEDIA`. **Increment 2b** adds native **video** (Kotlin
     `CallVideo`: camera publish/flip + remote/local `TextureViewRenderer` tiles hole-punched behind a transparent
-    WebView), gated by `ANDROID_NATIVE_VIDEO`; screen-share (MediaProjection) is still pending.
+    WebView), gated by `ANDROID_NATIVE_VIDEO`. **Increment 2c** adds **screen-share** (MediaProjection grant →
+    LiveKit `setScreenShareEnabled`; LiveKit's own `mediaProjection` foreground service) + **pinch-zoom** of a
+    received shared screen (web forwards the gesture under hole-punch → renderer transform).
   - `audio-route` (iOS audio output routing), `media-library` (save to Photos/gallery), `share-inbox` (inbound
     share sheet), `file-opener` (native Quick Look / open-with).
 - **iOS build:** Capacitor 8 + **SPM** (CocoaPods retired); Xcode 26; a share extension + a broadcast extension.
@@ -203,6 +205,10 @@ Bump the **Last updated** date at the top and add a line to the Changelog below.
 
 ## Changelog
 
+- **2026-11-03 (rev 6)** — Android native call **screen-share** (Increment 2c): `CallMedia.setScreenShareEnabled`
+  (MediaProjection → LiveKit; SDK-provided `mediaProjection` foreground service) + plugin `startScreenShare`/
+  `stopScreenShare` (permission via `startActivityForResult`), and **pinch-zoom** for a received shared screen
+  (`CallVideo.setTileZoom`). APK-only — no server/web change.
 - **2026-11-03 (rev 5)** — Reliability: Postgres pool safety timeouts (`connectionTimeoutMillis`,
   `statement_timeout`, `idle_in_transaction_session_timeout`, max 10→20) so a saturated pool fails fast instead
   of hanging forever; and a **pre-deploy HTML syntax guard** (`server/tools/check-syntax.js`) run in the Docker