fix(external-llm): correct o3 and glm-4.7 tiers

- github-copilot/o3: opus -> sonnet-equivalent
- zai-coding-plan/glm-4.7: sonnet -> opus-equivalent

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

state/model-policy.json

@@ -137,7 +137,7 @@
       "cli": "opencode",
       "cli_args": ["-m", "zai-coding-plan/glm-4.7"],
       "use_cases": ["code-generation"],
-      "tier": "sonnet-equivalent"
+      "tier": "opus-equivalent"
     },
     "github-copilot/gemini-3-pro-preview": {
       "cli": "opencode",
@@ -155,7 +155,7 @@
       "cli": "opencode",
       "cli_args": ["-m", "github-copilot/o3"],
       "use_cases": ["complex-reasoning"],
-      "tier": "opus-equivalent"
+      "tier": "sonnet-equivalent"
     },
     "opencode/big-pickle": {
       "cli": "opencode",