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_122.md

@@ -0,0 +1,30 @@
+# Task ID: 122
+
+**Title:** Update clearAllTables test helper
+
+**Status:** pending
+
+**Dependencies:** 117, 118, 119, 120, 121
+
+**Priority:** high
+
+**Description:** Add deleteMany calls for all new models to clearAllTables in src/db/tests/helpers.ts
+
+**Details:**
+
+In src/db/tests/helpers.ts clearAllTables function:
+1. Add deleteMany for TaskEvent (child first)
+2. Add deleteMany for TaskVerdict
+3. Add deleteMany for AgentSession
+4. Add deleteMany for Task
+5. Add deleteMany for EpicTaskEdge
+6. Add deleteMany for EpicTask
+7. Add deleteMany for Epic
+8. Add deleteMany for CodeRepo
+9. Add deleteMany for AgentProject
+10. Order matters: delete children before parents to avoid FK violations
+11. Follow existing pattern in the file
+
+**Test Strategy:**
+
+Run existing test suite to verify clearAllTables works correctly with new models. Add explicit test that creates rows in all new tables then calls clearAllTables and verifies tables are empty.