fix(project): stabilize project deletion

- Guard renderer project list/get against stale initial loads
- Retry project zip/cache removal to handle transient Windows locks
- Surface deletion failures in UI and add regression tests

Made-with: Cursor

app/main/project/fsRetry.ts

@@ -0,0 +1,32 @@
+type RmLike = (path: string, opts: { recursive?: boolean; force?: boolean }) => Promise<void>;
+
+function isRetryableRmError(err: unknown): boolean {
+  if (!err || typeof err !== 'object') return false;
+  const code = (err as { code?: unknown }).code;
+  return code === 'EBUSY' || code === 'EPERM' || code === 'EACCES';
+}
+
+export async function rmWithRetries(
+  rm: RmLike,
+  targetPath: string,
+  opts: { recursive?: boolean; force?: boolean },
+  retries = 6,
+): Promise<void> {
+  let attempt = 0;
+  // Windows: file locks/antivirus/indexers can cause transient EPERM/EBUSY.
+  // We retry a few times before surfacing the error.
+  // Delays: 20, 40, 80, 160, 320, 640ms (capped by retries).
+  for (;;) {
+    try {
+      await rm(targetPath, opts);
+      return;
+    } catch (e) {
+      attempt += 1;
+      if (attempt > retries || !isRetryableRmError(e)) {
+        throw e;
+      }
+      const delayMs = Math.min(800, 20 * 2 ** (attempt - 1));
+      await new Promise((r) => setTimeout(r, delayMs));
+    }
+  }
+}