merge: AgentProject membership — the junction is now load-bearing

Merges feat/agent-project-membership (task 166/152). An agent can finally join
many projects: membership routes, per-membership role and optional brain
override, chat resolving context from the membership, and CLI attach-agent /
detach-agent / get memberships. The legacy Agent.projectId fallback is kept for
this release as the schema comment promises.

Conflict resolved in main.ts: that branch added its RBAC case to
mapUrlToPermission inline, while this branch had extracted the function to
middleware/url-permission.ts so it could be tested. Kept the extraction and
ported the case into it — joining a team is `edit:agents:<name>`, not
`create:agents`, which is the authority to mint a whole agent.

Also fixes something the extraction makes possible. security.test.ts contained a
hand-copied reproduction of mapUrlToPermission, because main.ts self-invokes
main() and nothing in it was importable. A security test asserting against a
copy stops testing the system the moment the real one changes, and this copy had
already drifted. It now imports the real function; all 18 assertions still pass,
against the code that actually runs.

Local: build clean, workspace 2550 passed, lint unchanged at 794 errors.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4wNHWf7xSwnZCWpJcyv9p

.taskmaster/tasks/task_047.md

@@ -0,0 +1,61 @@
+# Task ID: 47
+
+**Title:** Implement session state management for gating
+
+**Status:** done
+
+**Dependencies:** 39 ✓
+
+**Priority:** high
+
+**Description:** Extend the McpRouter to track per-session gating state including gated status, accumulated tags, and retrieved prompts set.
+
+**Details:**
+
+1. Update `/src/mcplocal/src/router.ts` to add session state:
+   ```typescript
+   interface SessionState {
+     gated: boolean;           // starts true if project is gated
+     tags: string[];           // accumulated from begin_session + read_prompts
+     retrievedPrompts: Set<string>;  // prompts already sent (avoid duplicates)
+   }
+   
+   export class McpRouter {
+     private sessionStates: Map<string, SessionState> = new Map();
+     
+     getSessionState(sessionId: string): SessionState {
+       if (!this.sessionStates.has(sessionId)) {
+         this.sessionStates.set(sessionId, {
+           gated: this.projectConfig?.gated ?? true,
+           tags: [],
+           retrievedPrompts: new Set(),
+         });
+       }
+       return this.sessionStates.get(sessionId)!;
+     }
+     
+     ungateSession(sessionId: string): void {
+       const state = this.getSessionState(sessionId);
+       state.gated = false;
+     }
+     
+     addRetrievedPrompts(sessionId: string, names: string[]): void {
+       const state = this.getSessionState(sessionId);
+       names.forEach(n => state.retrievedPrompts.add(n));
+     }
+   }
+   ```
+
+2. Clean up session state when session closes
+
+3. Handle session state for non-gated projects (gated=false from start)
+
+**Test Strategy:**
+
+- Unit test: New session starts with gated=true for gated project
+- Unit test: New session starts with gated=false for non-gated project
+- Unit test: ungateSession changes gated to false
+- Unit test: addRetrievedPrompts adds to set
+- Unit test: retrievedPrompts prevents duplicates
+- Unit test: Session state isolated per sessionId
+- Unit test: Session cleanup removes state