feat: centralized error reporting → GitHub Issues

- PHP (api/index.php): hardcode GH_ISSUE_TOKEN/GH_REPO constants at top of
  file (before exception handler runs); fix $fp_ variable interpolation bug;
  global set_exception_handler + register_shutdown_function; reportError()
  endpoint (POST ?action=report_error) with rate limiting, local log, dedup
  via fingerprint search on GitHub Issues API

- Kiosk (ErrorReporter.kt): add crash persistence – saves crash payload to
  SharedPreferences before network POST, clears on success, retries as
  'uncaught-exception-survived' on next launch via sendPendingCrash() in init()

- Scale Gateway: new ErrorReporter.kt – calls GitHub Issues API directly
  (no relay needed, token hardcoded, scoped Issues R+W only); crash
  persistence via SharedPreferences; MainActivity.kt hooked at onCreate,
  startGatewayServer catch, onError (BLE errors)

Tested end-to-end: issues #3-#6 created and closed during QA.

.env.example

@@ -21,10 +21,5 @@ TTS_CONTENT_TYPE=application/json
 TTS_PAYLOAD_KEY=message
 TTS_ENABLED=false
 
-# GitHub Error Reporting (optional but recommended)
-# Creates GitHub Issues automatically on crashes/errors from app, kiosk and server.
-# Create a fine-grained PAT at https://github.com/settings/tokens?type=beta
-#   → Only selected repos: EverShelf
-#   → Permissions: Issues (Read+Write), Metadata (Read-only)
-GITHUB_ISSUE_TOKEN=
-GITHUB_REPO=dadaloop82/EverShelf
+# GitHub Error Reporting: token is hardcoded in api/index.php (same for all clients).
+# No .env entry needed — update GH_ISSUE_TOKEN constant in api/index.php to rotate.