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_117.md

@@ -0,0 +1,25 @@
+# Task ID: 117
+
+**Title:** Add Epic, EpicTask, EpicTaskEdge Prisma models
+
+**Status:** pending
+
+**Dependencies:** None
+
+**Priority:** high
+
+**Description:** Add Epic, EpicTask, EpicTaskEdge models with enums EpicStatus and EpicTaskStatus to schema.prisma following PRD specifications
+
+**Details:**
+
+In src/db/prisma/schema.prisma add:
+1. enum EpicStatus { open, delivered, delivered_with_tradeoffs, cancelled }
+2. enum EpicTaskStatus { todo, in_progress, done, cancelled }
+3. model Epic with: id, name, description, content (@db.Text), doneCriteria (Json), acceptedTradeoffs (Json), projectId, status, semver, currentRevisionId, ownerId, version, createdAt, updatedAt. Relations: project, owner (User), epicTasks[]. @@unique([name, projectId]), @@index([projectId]), @@index([name])
+4. model EpicTask with: id, name, description, epicId, doneCriteria (Json), status, ownerId, version, createdAt, updatedAt. Relations: epic, owner, tasks[], dependsOn (EpicTaskEdge[]), blocks (EpicTaskEdge[]). @@unique([name, epicId]), @@index([epicId])
+5. model EpicTaskEdge with: id, fromId, toId, createdAt. Relations using @relation names. @@unique([fromId, toId]), @@index([fromId]), @@index([toId])
+6. Add reverse relations to User and Project models
+
+**Test Strategy:**
+
+Schema tests in src/db/tests/: create Epic, verify unique constraint on (name, projectId), test cascade delete from Project, test EpicTask creation with Epic reference, test EpicTaskEdge uniqueness.