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_153.md

@@ -0,0 +1,24 @@
+# Task ID: 153
+
+**Title:** CLI tasks accept and reject commands
+
+**Status:** pending
+
+**Dependencies:** 131, 149
+
+**Priority:** medium
+
+**Description:** Add mcpctl tasks accept and reject commands for human approval gate
+
+**Details:**
+
+In src/cli/src/commands/ add or extend:
+1. mcpctl tasks accept NAME [--note TEXT] - call POST /tasks/:id/accept, triggers merge
+2. mcpctl tasks reject NAME --note TEXT - call POST /tasks/:id/reject, note required
+3. Resolve task name to id via API
+4. Print result: merge URL on success, error message on failure
+5. Accept should not require going to git - the CLI is the approval surface
+
+**Test Strategy:**
+
+Unit tests: test accept sends correct API call, test reject requires note flag, test output formatting.