feat(M3-008): add model capability matrix and ModelCapability type

Defines a per-model capability matrix for all 10 target models across
anthropic, openai, zai, and ollama providers. Adds the ModelCapability
interface to @mosaic/types and exports lookup helpers (getModelCapability,
findModelsByCapability, getModelsByProvider, getAllModels) from the
gateway agent module to support capability-aware routing.

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

packages/types/src/provider/index.ts

@@ -1,3 +1,22 @@
+/** Per-model capability metadata used by the routing engine */
+export interface ModelCapability {
+  id: string;
+  provider: string;
+  displayName: string;
+  tier: 'cheap' | 'standard' | 'premium' | 'local';
+  contextWindow: number;
+  maxOutputTokens: number;
+  capabilities: {
+    tools: boolean;
+    vision: boolean;
+    streaming: boolean;
+    reasoning: boolean;
+    embedding: boolean;
+  };
+  costPer1kInput?: number;
+  costPer1kOutput?: number;
+}
+
 /** Known built-in LLM provider identifiers */
 export type KnownProvider =
   | 'anthropic'