feat(FN-1147): rehydrate AI sessions across server restarts

- Add recoverable-session querying in AiSessionStore and cover it with targeted store tests
- Persist resume context (ip, initial plan, mission metadata) and rebuild planning/subtask/mission sessions from SQLite rows
- Rehydrate recoverable sessions at server startup and resume planning/mission interviews by recreating agents with replayed conversation context
- Update API flows to pass project root context and clean in-memory sessions when persisted sessions are deleted, with comprehensive regression tests

packages/dashboard/src/ai-session-store.ts

@@ -168,6 +168,30 @@ export class AiSessionStore extends EventEmitter<AiSessionStoreEvents> {
       .all() as unknown as AiSessionSummary[];
   }
 
+  /**
+   * List recoverable sessions for in-memory rehydration.
+   * Returns full rows for sessions still in progress.
+   */
+  listRecoverable(projectId?: string): AiSessionRow[] {
+    if (projectId) {
+      return this.db
+        .prepare(
+          `SELECT * FROM ai_sessions
+           WHERE status IN ('generating', 'awaiting_input') AND projectId = ?
+           ORDER BY updatedAt DESC`,
+        )
+        .all(projectId) as unknown as AiSessionRow[];
+    }
+
+    return this.db
+      .prepare(
+        `SELECT * FROM ai_sessions
+         WHERE status IN ('generating', 'awaiting_input')
+         ORDER BY updatedAt DESC`,
+      )
+      .all() as unknown as AiSessionRow[];
+  }
+
   /**
    * Delete a session by ID. Emits `ai_session:deleted`.
    */