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>

temp_cleanup.py

@@ -37,11 +37,12 @@ DIR_PATTERNS = [
     "mongodb-memory-server*",           # MongoDB Memory Server binaries
     "ng-*",                             # Angular CLI temp directories
     "scoped_dir*",                      # Chrome/Chromium temp directories
+    "node-compile-cache",               # Node.js V8 compile cache directory
 ]
 
 # File patterns to clean up (glob patterns)
 FILE_PATTERNS = [
-    ".78912*.node",   # Node.js native module cache (major space consumer, ~7MB each)
+    ".[0-9a-f]*.node",   # Node.js/V8 compile cache files (~7MB each, varying hex prefixes)
     "claude-*-cwd",   # Claude CLI working directory temp files
     "mat-debug-*.log",  # Material/Angular debug logs
 ]
@@ -122,6 +123,54 @@ def cleanup_stale_temp(max_age_seconds: int = MAX_AGE_SECONDS) -> dict:
     return stats
 
 
+def cleanup_project_screenshots(project_dir: Path, max_age_seconds: int = 300) -> dict:
+    """
+    Clean up stale screenshot files from the project root.
+
+    Playwright browser verification can leave .png files in the project
+    directory. This removes them after they've aged out (default 5 minutes).
+
+    Args:
+        project_dir: Path to the project directory.
+        max_age_seconds: Maximum age in seconds before a screenshot is deleted.
+                        Defaults to 5 minutes (300 seconds).
+
+    Returns:
+        Dictionary with cleanup statistics (files_deleted, bytes_freed, errors).
+    """
+    cutoff_time = time.time() - max_age_seconds
+    stats: dict = {"files_deleted": 0, "bytes_freed": 0, "errors": []}
+
+    screenshot_patterns = [
+        "feature*-*.png",
+        "screenshot-*.png",
+        "step-*.png",
+    ]
+
+    for pattern in screenshot_patterns:
+        for item in project_dir.glob(pattern):
+            if not item.is_file():
+                continue
+            try:
+                mtime = item.stat().st_mtime
+                if mtime < cutoff_time:
+                    size = item.stat().st_size
+                    item.unlink(missing_ok=True)
+                    if not item.exists():
+                        stats["files_deleted"] += 1
+                        stats["bytes_freed"] += size
+                        logger.debug(f"Deleted project screenshot: {item}")
+            except Exception as e:
+                stats["errors"].append(f"Failed to delete {item}: {e}")
+                logger.debug(f"Failed to delete screenshot {item}: {e}")
+
+    if stats["files_deleted"] > 0:
+        mb_freed = stats["bytes_freed"] / (1024 * 1024)
+        logger.info(f"Screenshot cleanup: {stats['files_deleted']} files, {mb_freed:.1f} MB freed")
+
+    return stats
+
+
 def _get_dir_size(path: Path) -> int:
     """Get total size of a directory in bytes."""
     total = 0