feat: fix slash commands, add badge UI, multi-provider management

Slash commands:
- Fix skills not appearing (removed non-existent `enabled` filter)
- Add badge/capsule UI for prompt-type commands (/compact, /review, etc.)
- SDK-native commands sent directly; CLI-only commands expanded to prompts
- /clear now resets SDK session and clears database messages
- /cost shows actual aggregated token usage statistics
- Keyboard: Backspace/Escape to remove badge, arrow keys auto-scroll popover
- Add /memory command for editing CLAUDE.md

Multi-provider management:
- CRUD API for API providers with SQLite storage
- ProviderManager UI with quick presets (GLM, Kimi, MiniMax, etc.)
- Dynamic model labels based on active provider
- Environment variable injection with conflict resolution

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

src/types/index.ts

@@ -93,6 +93,51 @@ export interface Setting {
   value: string;
 }
 
+// ==========================================
+// API Provider Types
+// ==========================================
+
+export interface ApiProvider {
+  id: string;
+  name: string;
+  provider_type: string; // 'anthropic' | 'openrouter' | 'bedrock' | 'vertex' | 'custom'
+  base_url: string;
+  api_key: string;
+  is_active: number; // SQLite boolean: 0 or 1
+  sort_order: number;
+  extra_env: string; // JSON string of Record<string, string>
+  notes: string;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface CreateProviderRequest {
+  name: string;
+  provider_type?: string;
+  base_url?: string;
+  api_key?: string;
+  extra_env?: string;
+  notes?: string;
+}
+
+export interface UpdateProviderRequest {
+  name?: string;
+  provider_type?: string;
+  base_url?: string;
+  api_key?: string;
+  extra_env?: string;
+  notes?: string;
+  sort_order?: number;
+}
+
+export interface ProvidersResponse {
+  providers: ApiProvider[];
+}
+
+export interface ProviderResponse {
+  provider: ApiProvider;
+}
+
 // ==========================================
 // Token Usage
 // ==========================================