fix: prevent temp file accumulation during long agent runs

Address three issues reported after overnight AutoForge runs:
1. ~193GB of .node files in %TEMP% from V8 compile caching
2. Stale npm artifact folders on drive root when %TEMP% fills up
3. PNG screenshot files left in project root by Playwright

Changes:
- Widen .node cleanup glob from ".78912*.node" to ".[0-9a-f]*.node"
  to match all V8 compile cache hex prefixes
- Add "node-compile-cache" directory to temp cleanup patterns
- Set NODE_COMPILE_CACHE="" in all subprocess environments (client.py,
  parallel_orchestrator.py, process_manager.py) to disable V8 compile
  caching at the source
- Add cleanup_project_screenshots() to remove stale .png files from
  project directories (feature*-*.png, screenshot-*.png, step-*.png)
- Run cleanup_stale_temp() at server startup in lifespan()
- Add _run_inter_session_cleanup() to orchestrator, called after each
  agent completes (both coding and testing paths)
- Update coding and testing prompt templates to instruct agents to use
  inline (base64) screenshots only, never saving files to disk

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/main.py

@@ -61,6 +61,17 @@ UI_DIST_DIR = ROOT_DIR / "ui" / "dist"
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     """Lifespan context manager for startup and shutdown."""
+    # Startup - clean up stale temp files (Playwright profiles, .node cache, etc.)
+    try:
+        from temp_cleanup import cleanup_stale_temp
+        stats = cleanup_stale_temp()
+        if stats["dirs_deleted"] > 0 or stats["files_deleted"] > 0:
+            mb_freed = stats["bytes_freed"] / (1024 * 1024)
+            logger.info("Startup temp cleanup: %d dirs, %d files, %.1f MB freed",
+                        stats["dirs_deleted"], stats["files_deleted"], mb_freed)
+    except Exception as e:
+        logger.warning("Startup temp cleanup failed (non-fatal): %s", e)
+
     # Startup - clean up orphaned lock files from previous runs
     cleanup_orphaned_locks()
     cleanup_orphaned_devserver_locks()