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_054.md

@@ -0,0 +1,58 @@
+# Task ID: 54
+
+**Title:** Create mcpctl-system project with system prompts
+
+**Status:** done
+
+**Dependencies:** 40 ✓, 39 ✓
+
+**Priority:** high
+
+**Description:** Implement bootstrap logic to create the mcpctl-system project and its required system prompts on first startup, with protection against deletion.
+
+**Details:**
+
+1. Create seed migration or startup hook:
+   ```typescript
+   async function bootstrapSystemProject() {
+     const systemProject = await projectRepo.findByName('mcpctl-system');
+     if (systemProject) return; // Already exists
+     
+     // Create mcpctl-system project
+     const project = await projectRepo.create({
+       name: 'mcpctl-system',
+       description: 'System prompts for mcpctl gating and encouragement',
+       gated: false,  // System project is not gated
+       ownerId: SYSTEM_USER_ID,
+     });
+     
+     // Create required system prompts
+     const systemPrompts = [
+       { name: 'gate-instructions', priority: 10, content: GATE_INSTRUCTIONS },
+       { name: 'gate-encouragement', priority: 10, content: GATE_ENCOURAGEMENT },
+       { name: 'read-prompts-reminder', priority: 10, content: READ_PROMPTS_REMINDER },
+       { name: 'gate-intercept-preamble', priority: 10, content: GATE_INTERCEPT_PREAMBLE },
+       { name: 'session-greeting', priority: 10, content: SESSION_GREETING },
+     ];
+     
+     for (const p of systemPrompts) {
+       await promptRepo.create({ ...p, projectId: project.id });
+     }
+   }
+   ```
+
+2. Add delete protection in prompt delete endpoint:
+   - Check if prompt belongs to mcpctl-system
+   - Return 403 error if attempting to delete system prompt
+
+3. Define default content for each system prompt per PRD
+
+**Test Strategy:**
+
+- Unit test: System project created on first startup
+- Unit test: All 5 system prompts created
+- Unit test: Subsequent startups don't duplicate
+- Unit test: Delete system prompt returns 403
+- Unit test: System prompts have priority 10
+- Unit test: mcpctl-system project has gated=false
+- Integration test: End-to-end bootstrap flow