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_124.md

@@ -0,0 +1,27 @@
+# Task ID: 124
+
+**Title:** Epic service layer with revision integration
+
+**Status:** pending
+
+**Dependencies:** 123
+
+**Priority:** medium
+
+**Description:** Create EpicService with CRUD operations, revision tracking via ResourceRevision, and done-criteria roll-up logic
+
+**Details:**
+
+Create src/mcpd/src/services/epic.service.ts:
+1. Inject EpicRepository, ResourceRevisionRepository, ProjectRepository
+2. create(): validate project exists, create Epic, create initial ResourceRevision with resourceType:'epic'
+3. update(): bump semver, create ResourceRevision, update currentRevisionId
+4. getById(), getByName(), listByProject()
+5. addTradeoff(): append to acceptedTradeoffs JSON array
+6. computeStatus(): roll up EpicTask completion to determine if Epic is delivered/delivered_with_tradeoffs
+7. getRoadmap(): return epictask graph with per-node completeness percentages
+8. Follow PromptService pattern for revision integration
+
+**Test Strategy:**
+
+Unit tests: test create writes revision, test update bumps semver and writes revision, test addTradeoff appends correctly, test computeStatus logic for all EpicStatus values.