address review: add MODEL_SPECS entries for new claude/kimi/mimo models

Per gemini-code-assist review on #2163, the registry contextLength/
maxOutputTokens values were being silently capped to 8192 by
capMaxOutputTokens() because the model IDs were absent from MODEL_SPECS,
falling back to __default__.maxOutputTokens. Adds entries with
matching limits :

- claude-opus-4-5-20251101 : 64000 max_out (overrides prefix-match to
  claude-opus-4-5 which has 32768)
- claude-opus-4-6 : 128000 max_out, 1M context tier
- claude-sonnet-4-6, claude-sonnet-4-5-20250929, claude-haiku-4-5-20251001
  : 64000 max_out each
- kimi-k2.6 : 262144 max_out, 262144 context, with aliases for
  kimi-k2.6-thinking and kimi-for-coding
- mimo-v2.5-pro / mimo-v2.5 : 131072 max_out, 1048576 context
- mimo-v2-omni : 131072 max_out, 262144 context
- mimo-v2-flash : 65536 max_out, 262144 context

Each entry carries `aliases` where dot-notation variants exist
(e.g. claude-opus-4.6), so capMaxOutputTokens resolves them via the
explicit alias lookup before falling back to the prefix-match path.

src/shared/constants/modelSpecs.ts

@@ -79,6 +79,27 @@ export const MODEL_SPECS: Record<string, ModelSpec> = {
     supportsVision: true,
   },
 
+  // ── Claude Opus 4.5 (full ID — overrides prefix match on claude-opus-4-5) ──
+  "claude-opus-4-5-20251101": {
+    maxOutputTokens: 64000,
+    contextWindow: 200000,
+    defaultThinkingBudget: 10000,
+    thinkingBudgetCap: 32000,
+    supportsThinking: true,
+    supportsTools: true,
+    supportsVision: true,
+  },
+
+  // ── Claude Opus 4.6 (1M context tier) ───────────────────────────
+  "claude-opus-4-6": {
+    maxOutputTokens: 128000,
+    contextWindow: 1000000,
+    supportsThinking: true,
+    supportsTools: true,
+    supportsVision: true,
+    aliases: ["claude-opus-4.6"],
+  },
+
   // ── Claude Opus 4.7 ─────────────────────────────────────────────
   "claude-opus-4-7": {
     maxOutputTokens: 128000,
@@ -89,6 +110,67 @@ export const MODEL_SPECS: Record<string, ModelSpec> = {
     aliases: ["claude-opus-4.7"],
   },
 
+  // ── Claude Sonnet 4.6 ───────────────────────────────────────────
+  "claude-sonnet-4-6": {
+    maxOutputTokens: 64000,
+    contextWindow: 200000,
+    supportsThinking: true,
+    supportsTools: true,
+    supportsVision: true,
+    aliases: ["claude-sonnet-4.6"],
+  },
+
+  // ── Claude Sonnet 4.5 ───────────────────────────────────────────
+  "claude-sonnet-4-5-20250929": {
+    maxOutputTokens: 64000,
+    contextWindow: 200000,
+    supportsThinking: true,
+    supportsTools: true,
+    supportsVision: true,
+    aliases: ["claude-sonnet-4.5"],
+  },
+
+  // ── Claude Haiku 4.5 ────────────────────────────────────────────
+  "claude-haiku-4-5-20251001": {
+    maxOutputTokens: 64000,
+    contextWindow: 200000,
+    supportsThinking: true,
+    supportsTools: true,
+    supportsVision: true,
+    aliases: ["claude-haiku-4.5"],
+  },
+
+  // ── Kimi K2.6 (Moonshot Kimi Code OAuth — 262K native) ──────────
+  "kimi-k2.6": {
+    maxOutputTokens: 262144,
+    contextWindow: 262144,
+    supportsThinking: true,
+    supportsTools: true,
+    aliases: ["kimi-k2.6-thinking", "kimi-for-coding"],
+  },
+
+  // ── Xiaomi MiMo V2.5 (1M context, consensus across 7+ sync sources) ──
+  "mimo-v2.5-pro": {
+    maxOutputTokens: 131072,
+    contextWindow: 1048576,
+    supportsTools: true,
+  },
+  "mimo-v2.5": {
+    maxOutputTokens: 131072,
+    contextWindow: 1048576,
+    supportsTools: true,
+  },
+  "mimo-v2-omni": {
+    maxOutputTokens: 131072,
+    contextWindow: 262144,
+    supportsTools: true,
+  },
+  "mimo-v2-flash": {
+    maxOutputTokens: 65536,
+    contextWindow: 262144,
+    supportsTools: true,
+  },
+
   // Defaults
   __default__: {
     maxOutputTokens: 8192,