feat(packaging): ship Linux embedded MPV frame-copy runtime (#1200)

* docs: design Linux frame-copy packaging

* docs: plan Linux frame-copy packaging

* feat(packaging): define Linux frame-copy profiles

* fix(packaging): reject inherited profile names

* feat(embedded-mpv): validate staged Linux runtime

* fix(embedded-mpv): require Linux source packages

* fix(embedded-mpv): harden Linux runtime staging

* feat(embedded-mpv): build LGPL Linux runtime

* fix(embedded-mpv): pin Linux runtime inputs

* feat(embedded-mpv): build relocatable Linux helper

* fix(embedded-mpv): require bundled Linux runtime

* fix(embedded-mpv): make Linux runtime portable

* feat(packaging): ship Linux frame-copy artifacts

* fix(embedded-mpv): verify Linux helper linkage

* fix(packaging): enforce Linux frame-copy isolation

* fix(embedded-mpv): pin Linux display data

* docs(embedded-mpv): document Linux frame-copy packaging

* feat(embedded-mpv): probe Linux frame-copy runtime

* test(embedded-mpv): smoke packaged Linux frame-copy

* docs(embedded-mpv): clarify Linux system runtime baseline

* fix(embedded-mpv): harden Linux runtime capability gate

* ci: verify Linux frame-copy packages

* test(embedded-mpv): harden packaged Linux smoke

* test(embedded-mpv): preserve packaged GL mode

* test(packaging): harden Linux package probes

* fix(embedded-mpv): enable private Snap shared memory

* fix(embedded-mpv): sanitize Linux helper environment

* fix(packaging): enforce private Snap memory semantics

* fix(packaging): reject ambiguous Snap memory metadata

* fix(embedded-mpv): prioritize trusted Snap GL

* fix(packaging): reject advanced Snap YAML semantics

* fix(packaging): reject arbitrary Snap YAML aliases

* feat(packaging): ship Linux runtime license notices

* docs(embedded-mpv): document Linux runtime distribution

* fix(packaging): parse Snap trailing comments safely

* fix(release): gate Snap publish on public source release

* fix(packaging): strip VCS metadata from source bundle

* docs(packaging): clarify Linux source release gate

* test(embedded-mpv): smoke missing bundled libmpv

* style(embedded-mpv): format final validation inputs

* fix(e2e): satisfy fixture index signature typing

* fix(ci): declare fontconfig gperf generator

* fix(embedded-mpv): hash runtime cache identities

* fix(packaging): harden Linux frame-copy delivery

* fix(packaging): tighten runtime delivery gates

* fix(ci): decouple Linux runtime matrix

* fix(packaging): harden Linux frame-copy delivery

* fix(packaging): validate Linux frame-copy runtimes

* fix(packaging): scope Snap Electron library checks

* feat(packaging): ship Linux frame-copy runtimes

* fix(packaging): improve Linux runtime smoke diagnostics

* fix(packaging): expose bounded helper probe details

* test(packaging): trace Snap EGL probe failures

* fix(packaging): prefer core22 ABI in Snap helper

* fix(packaging): bound helper probe capture

* fix(packaging): harden Linux frame-copy releases

* fix(packaging): canonicalize libplacebo submodule identity

* fix(packaging): make source archive inspection portable

* fix(packaging): harden Snap release verification

libs/shared/interfaces/src/lib/embedded-mpv-session.interface.ts

@@ -37,11 +37,16 @@ export interface EmbeddedMpvSupport {
     engine?: EmbeddedMpvEngine;
     /**
      * True when this machine could run the frame-copy engine (macOS arm64
-     * or Linux, with the helper binary present), regardless of whether it
-     * is active.
+     * or Linux x64, after its helper/runtime capability gate), regardless of
+     * whether it is active.
      * Drives the Settings toggle; switching engines requires an app restart.
      */
     frameCopyAvailable?: boolean;
+    /**
+     * Stable fail-closed capability reason when frameCopyAvailable is false.
+     * Intended for startup tracing and support diagnostics, not user copy.
+     */
+    frameCopyUnavailableReason?: string;
 }
 
 /**