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_102.md

@@ -0,0 +1,60 @@
+# Task ID: 102
+
+**Title:** Implement mcpctl cache stats Command
+
+**Status:** done
+
+**Dependencies:** 98 ✓
+
+**Priority:** low
+
+**Description:** Add CLI command to show cache statistics including hit rates, total size, and entry counts.
+
+**Details:**
+
+Create `src/cli/src/commands/cache-stats.ts`:
+
+```typescript
+import { Command } from 'commander';
+import { readdir, stat } from 'fs/promises';
+import { join } from 'path';
+
+const CACHE_DIR = join(process.env.HOME ?? '', '.mcpctl', 'cache', 'proxymodel');
+
+export function registerCacheStats(program: Command): void {
+  program
+    .command('cache stats')
+    .description('Show cache statistics')
+    .action(async () => {
+      try {
+        const files = await readdir(CACHE_DIR);
+        
+        let totalSize = 0;
+        let oldest = Date.now();
+        let newest = 0;
+        
+        for (const file of files) {
+          const filePath = join(CACHE_DIR, file);
+          const stats = await stat(filePath);
+          totalSize += stats.size;
+          oldest = Math.min(oldest, stats.mtimeMs);
+          newest = Math.max(newest, stats.mtimeMs);
+        }
+        
+        console.log(`Entries: ${files.length}`);
+        console.log(`Total size: ${formatSize(totalSize)}`);
+        console.log(`Oldest entry: ${formatAge(Date.now() - oldest)} ago`);
+        console.log(`Newest entry: ${formatAge(Date.now() - newest)} ago`);
+        
+        // Note: hit rate tracking would require runtime instrumentation
+        console.log('\nNote: Hit rate statistics require runtime instrumentation.');
+      } catch {
+        console.log('No cache data available');
+      }
+    });
+}
+```
+
+**Test Strategy:**
+
+CLI test: shows correct stats for populated cache, handles empty cache gracefully, size formatting is correct.