feat(passwd): mcpctl passwd + RBAC-gated password change

Restores the lost `mcpctl passwd` command and builds the backend it needs.

Backend (mcpd):
- POST /api/v1/users/me/password — self-service change, requires current
  password. Gated by a new `set-own-password` operation.
- PUT /api/v1/users/:id/password — admin reset of another user, gated by
  edit:users (admins have edit:*). Added users name-resolver for CUID→email.
- UserService.setPassword/verifyPassword; UserRepository.update accepts
  passwordHash + findByIdWithHash.

RBAC, no exceptions: self password change is a default, admin-revocable
permission. Every new user gets a `self-<id>` RbacDefinition granting
`set-own-password`, seeded on create + bootstrap, gated by the
`allowSelfPasswordChange` system setting (stored in the mcpctl-system-settings
secret, default ON; admins disable globally or revoke per-user).

CLI: src/cli/src/commands/passwd.ts (self vs admin paths) + completions.

Tests: users-password route tests (8), auth-bootstrap grant assertion,
passwd live smoke test. Full suite 2214 passing; zero new lint errors.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/cli/src/index.ts

@@ -25,6 +25,7 @@ import { createMigrateCommand } from './commands/migrate.js';
 import { createRotateCommand } from './commands/rotate.js';
 import { createReviewCommand } from './commands/review.js';
 import { createSkillsCommand } from './commands/skills.js';
+import { createPasswdCommand } from './commands/passwd.js';
 import { ApiClient, ApiError } from './api-client.js';
 import { loadConfig } from './config/index.js';
 import { loadCredentials } from './auth/index.js';
@@ -257,6 +258,11 @@ export function createProgram(): Command {
     log: (...args) => console.log(...args),
   }));
 
+  program.addCommand(createPasswdCommand({
+    client,
+    log: (...args) => console.log(...args),
+  }));
+
   program.addCommand(createBackupCommand({
     client,
     log: (...args) => console.log(...args),