chore(player): a script for the conformance suite

The desktop runner needed a hand-generated fixture and the Android one needed
`-x :app:rustBuildUniversalDebug`, which nobody was going to remember. Both are
now `bun run test:player` and `bun run test:player:android`.

The fixture is generated on first use rather than committed: no media in the
repo, and an exact duration, which the seek assertions depend on.

The gradle exclusion carries its reason inline — raw gradle drives the Rust
build through Tauri's android-studio-script, which expects a dev-server address
file that only exists under `tauri android dev`, and the library already in
jniLibs is what the test process loads.

package.json

@@ -53,7 +53,9 @@
     "traces:markdown": "bun run scripts/extract-traces.ts --format markdown > docs/traceability.md",
     "traces:coverage": "bun run scripts/extract-traces.ts --format coverage",
     "traces:validate": "bun run scripts/extract-traces.ts --format validate",
-    "release:notes": "bun run scripts/release-notes.ts"
+    "release:notes": "bun run scripts/release-notes.ts",
+    "test:player": "./scripts/test-player-conformance.sh",
+    "test:player:android": "./scripts/test-player-conformance.sh android"
   },
   "dependencies": {
     "@tauri-apps/api": "^2.11.1",