perf(electron): compile the main-process bundle from a V8 code cache (#1696)

main.js is now a small entry that enables Node's on-disk V8 compile cache under userData/v8-compile-cache and then requires the application bundle main.app.js. Warm launches reach app.whenReady about 13 ms sooner at the median; IPTVNATOR_DISABLE_COMPILE_CACHE=1 turns it off and IPTVNATOR_COMPILE_CACHE_DIR relocates it.

Packaging now ships main.app.js explicitly and verify:package-layout requires the main-process entry files in app.asar, because nx-electron copies the backend through an allowlist. The Xtream benchmark build identity hashes both the launcher and the bundle.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/development/electron-debugging.md

@@ -32,6 +32,7 @@ IPTVNATOR_TRACE_STARTUP=1 pnpm nx serve electron-backend
     - `IPTVNATOR_TRACE_RENDERER_CONSOLE=1` mirrors renderer console output into the Electron terminal
     - `IPTVNATOR_PERF_CAPTURE=1` enables development/test-only, redacted M3U and Xtream preload IPC request/completion markers plus count-only M3U acquire/parse/normalize, Xtream main network/JSON-transform/success-response-ready/cancel-dispatch, and renderer store phase capture; renderer wrappers emit only while the benchmark installs its Symbol hook, benchmark tooling sets the flag explicitly, and production launches must leave it unset
     - `IPTVNATOR_PERF_WORKER_PROFILING=1` enables development/test-only, request-scoped worker receive/work/response-post timestamps, thread CPU, event-loop utilization/delay, count-only playlist serialization/SQLite write/read/deserialization plus Xtream category/content/cache-clear/delete/in-source-search phase events, profiling-only worker cancel-receipt acknowledgements, valid-sample-counted isolate peak memory, and the database worker's idle-only one-shot post-GC heap probe; overlapping database requests are explicitly invalidated instead of misattributed, the performance benchmark sets the flag automatically, and production launches must leave it unset
+    - `IPTVNATOR_DISABLE_COMPILE_CACHE=1` disables the main-process V8 compile cache; `IPTVNATOR_COMPILE_CACHE_DIR=<dir>` relocates it. The startup trace reports the outcome as `compile-cache`
 
 - Settings, portal request/response, and trace payloads must use
   `@iptvnator/shared/logging` or the redacting portal logger before reaching
@@ -93,8 +94,17 @@ classifying a zero rendered-frame signal as an infrastructure flake.
 
 ## Main-process ownership
 
-The entry point is `apps/electron-backend/src/main.ts`; it bootstraps the database,
-registers events and creates the main window. The preload is
+The process entry is `apps/electron-backend/src/main.entry.ts` (built to
+`dist/apps/electron-backend/main.js`): it enables the V8 compile cache under
+`userData/v8-compile-cache` and then requires the application bundle,
+`main.app.js`, built from `apps/electron-backend/src/main.ts`, which bootstraps
+the database, registers events and creates the main window. The cache is
+disposable; `IPTVNATOR_DISABLE_COMPILE_CACHE=1` turns it off and
+`IPTVNATOR_COMPILE_CACHE_DIR` relocates it (E2E runs keep it inside
+`IPTVNATOR_E2E_DATA_DIR`). nx-electron packages the backend through an
+allowlist, so `apps/electron-backend/project.json` lists `main.app.js` under the
+`files` option of the `package` and `make` targets, and `verify:package-layout`
+fails when either entry file is missing from `app.asar`. The preload is
 `apps/electron-backend/src/app/api/main.preload.ts`, with handlers under
 `apps/electron-backend/src/app/events/`. The window follows the saved startup mode
 (normal/maximized/fullscreen); `--fullscreen` overrides a single launch. Use