feat(db): move container config from filesystem to DB

Source of truth for container runtime config moves from
groups/<folder>/container.json to a new container_configs table.
The file becomes a materialized view written at spawn time.

- New container_configs table with scalar columns (provider, model,
  effort, image_tag, assistant_name, max_messages_per_prompt) and
  JSON columns (mcp_servers, packages_apt, packages_npm, skills,
  additional_mounts)
- Startup backfill seeds DB from existing container.json files
- materializeContainerJson() replaces readContainerConfig + ensureRuntimeFields
- Self-mod handlers (install_packages, add_mcp_server) write to DB
- Provider cascade simplified: session -> container_configs -> 'claude'
- ncl groups config-{get,update,add-mcp-server,remove-mcp-server,
  add-package,remove-package} custom operations
- restartAgentGroupContainers() helper for config change propagation
- Container side unchanged (still reads /workspace/agent/container.json)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/container-runner.test.ts

@@ -3,30 +3,25 @@ import { describe, expect, it } from 'vitest';
 import { resolveProviderName } from './container-runner.js';
 
 describe('resolveProviderName', () => {
-  it('prefers session over group and container.json', () => {
-    expect(resolveProviderName('codex', 'opencode', 'claude')).toBe('codex');
+  it('prefers session over container config', () => {
+    expect(resolveProviderName('codex', 'claude')).toBe('codex');
   });
 
-  it('falls back to group when session is null', () => {
-    expect(resolveProviderName(null, 'codex', 'claude')).toBe('codex');
-  });
-
-  it('falls back to container.json when session and group are null', () => {
-    expect(resolveProviderName(null, null, 'opencode')).toBe('opencode');
+  it('falls back to container config when session is null', () => {
+    expect(resolveProviderName(null, 'opencode')).toBe('opencode');
   });
 
   it('defaults to claude when nothing is set', () => {
-    expect(resolveProviderName(null, null, undefined)).toBe('claude');
+    expect(resolveProviderName(null, undefined)).toBe('claude');
   });
 
   it('lowercases the resolved name', () => {
-    expect(resolveProviderName('CODEX', null, null)).toBe('codex');
-    expect(resolveProviderName(null, 'OpenCode', null)).toBe('opencode');
-    expect(resolveProviderName(null, null, 'Claude')).toBe('claude');
+    expect(resolveProviderName('CODEX', null)).toBe('codex');
+    expect(resolveProviderName(null, 'Claude')).toBe('claude');
   });
 
   it('treats empty string as unset (falls through)', () => {
-    expect(resolveProviderName('', 'codex', null)).toBe('codex');
-    expect(resolveProviderName(null, '', 'opencode')).toBe('opencode');
+    expect(resolveProviderName('', 'opencode')).toBe('opencode');
+    expect(resolveProviderName(null, '')).toBe('claude');
   });
 });