feat: Add unified LiteLLM API management with dashboard UI and CLI integration

- Create ccw-litellm Python package with AbstractEmbedder and AbstractLLMClient interfaces
- Add BaseEmbedder abstraction and factory pattern to codex-lens for pluggable backends
- Implement API Settings dashboard page for provider credentials and custom endpoints
- Add REST API routes for CRUD operations on providers and endpoints
- Extend CLI with --model parameter for custom endpoint routing
- Integrate existing context-cache for @pattern file resolution
- Add provider model registry with predefined models per provider type
- Include i18n translations (en/zh) for all new UI elements

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ccw/src/templates/dashboard.html

@@ -336,6 +336,10 @@
                 <span class="nav-text flex-1" data-i18n="nav.codexLensManager">CodexLens</span>
                 <span class="badge px-2 py-0.5 text-xs font-semibold rounded-full bg-hover text-muted-foreground" id="badgeCodexLens">-</span>
               </li>
+              <li class="nav-item flex items-center gap-2 px-3 py-2.5 text-sm text-muted-foreground hover:bg-hover hover:text-foreground rounded cursor-pointer transition-colors" data-view="api-settings" data-tooltip="API Settings">
+                <i data-lucide="settings" class="nav-icon"></i>
+                <span class="nav-text flex-1" data-i18n="nav.apiSettings">API Settings</span>
+              </li>
               <!-- Hidden: Code Graph Explorer (feature disabled)
               <li class="nav-item flex items-center gap-2 px-3 py-2.5 text-sm text-muted-foreground hover:bg-hover hover:text-foreground rounded cursor-pointer transition-colors" data-view="graph-explorer" data-tooltip="Code Graph Explorer">
                 <i data-lucide="git-branch" class="nav-icon"></i>