feat: replace profiles with kubernetes-style secrets

Replace the confused Profile abstraction with a dedicated Secret resource
following Kubernetes conventions. Servers now have env entries with inline
values or secretRef references. Env vars are resolved and passed to
containers at startup (fixes existing gap).

- Add Secret CRUD (model, repo, service, routes, CLI commands)
- Server env: {name, value} or {name, valueFrom: {secretRef: {name, key}}}
- Add env-resolver utility shared by instance startup and config generation
- Remove all profile-related code (models, services, routes, CLI, tests)
- Update backup/restore for secrets instead of profiles
- describe secret masks values by default, --show-values to reveal

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/cli/tests/commands/instances.test.ts

@@ -45,12 +45,6 @@ describe('delete command', () => {
     expect(client.delete).toHaveBeenCalledWith('/api/v1/servers/srv-abc');
   });
 
-  it('deletes a profile', async () => {
-    const cmd = createDeleteCommand({ client, log });
-    await cmd.parseAsync(['profile', 'prof-1'], { from: 'user' });
-    expect(client.delete).toHaveBeenCalledWith('/api/v1/profiles/prof-1');
-  });
-
   it('deletes a project', async () => {
     const cmd = createDeleteCommand({ client, log });
     await cmd.parseAsync(['project', 'proj-1'], { from: 'user' });