fix(bridge): v16 terminal output filter + v15 stale LS auto-fix + heartbeat probe (v0.5.50) #task-619

- http-bridge v16: Block terminal OUTPUT as enriched cmd — if description has no prompt marker (> » $ #), it's stdout from code block, not an actual command. Prevents 'No extension.log found' etc. from reaching Discord.
- step-probe v15: Stale LS auto-detection — if all sessions are >5min old, periodically retry fixLSConnection(). Heartbeat probe every 10 polls to detect step changes when summary API returns frozen stepCount.
- extension.ts v15: fixLSConnection() fallback — match LS processes without --workspace_id (common after AG restart)

extension/package.json

@@ -2,7 +2,7 @@
   "name": "gravity-bridge",
   "displayName": "Gravity Bridge",
   "description": "Discord-based unified approval system for Antigravity AI interactions.",
-  "version": "0.5.47",
+  "version": "0.5.50",
   "publisher": "variet",
   "engines": {
     "vscode": "^1.100.0"