feat(codex): complete routed model catalogs

Codex treats the downloaded model catalog as a capability contract. Slug-only entries hide supported reasoning levels, can advertise invalid image inputs, and expose automatic or media-only models in the model picker. Generate complete route-aware metadata, preserve official manifests, filter non-agent models, and compute validators from the final catalog.

frontend/src/api/__tests__/codex.spec.ts

@@ -16,10 +16,34 @@ describe('Codex models API', () => {
   })
 
   it('fetches a manifest with the current API key without adding it to the catalog', async () => {
+    const manifest = {
+      models: [
+        {
+          slug: 'grok-4.6',
+          default_reasoning_level: 'high',
+          supported_reasoning_levels: [
+            { effort: 'low', description: 'Fast responses' },
+            { effort: 'xhigh', description: 'Extra-high reasoning depth' }
+          ],
+          input_modalities: ['text', 'image'],
+          model_messages: { instructions_template: 'Use the routed model.' }
+        },
+        {
+          slug: 'deepseek-v4-pro',
+          default_reasoning_level: 'high',
+          supported_reasoning_levels: [
+            { effort: 'low', description: 'Fast responses' },
+            { effort: 'max', description: 'Maximum reasoning depth' }
+          ],
+          input_modalities: ['text'],
+          model_messages: { instructions_template: 'Use the routed model.' }
+        }
+      ]
+    }
     const fetchMock = vi.fn().mockResolvedValue({
       ok: true,
       status: 200,
-      json: async () => ({ models: [{ slug: 'grok-4.6' }, { slug: 'deepseek-v4-pro' }] })
+      json: async () => manifest
     })
     vi.stubGlobal('fetch', fetchMock)
 
@@ -35,6 +59,10 @@ describe('Codex models API', () => {
       })
     )
     expect(result.modelCount).toBe(2)
+    expect(JSON.parse(result.content)).toEqual(manifest)
+    expect(result.content).toContain('"effort": "xhigh"')
+    expect(result.content).toContain('"input_modalities"')
+    expect(result.content).toContain('"instructions_template"')
     expect(result.content).not.toContain('sk-user-test')
   })