feat(model): add GPT-5.5 support for Codex provider (#880)

- Bump Codex provider defaults from gpt-5.4 to gpt-5.5 across all ModelConfigs
- Update codexplan alias to resolve to gpt-5.5
- Add gpt-5.5 and gpt-5.5-mini to model picker with reasoning effort mappings
- Add context window and max output token specs for gpt-5.5 family
- Add gpt-5.5 entries to COPILOT_MODELS registry
- Keep official OpenAI API preset at gpt-5.4 (API availability pending)
- Update codexShim tests to expect gpt-5.5 from codexplan alias

Co-authored-by: OpenClaude <openclaude@gitlawb.com>

src/services/api/codexShim.test.ts

@@ -88,7 +88,7 @@ describe('Codex provider config', () => {
 
     const resolved = resolveProviderRequest({ model: 'codexplan' })
     expect(resolved.transport).toBe('codex_responses')
-    expect(resolved.resolvedModel).toBe('gpt-5.4')
+    expect(resolved.resolvedModel).toBe('gpt-5.5')
     expect(resolved.reasoning).toEqual({ effort: 'high' })
     expect(resolved.baseUrl).toBe('https://chatgpt.com/backend-api/codex')
   })
@@ -114,7 +114,7 @@ describe('Codex provider config', () => {
 
     expect(resolved.transport).toBe('chat_completions')
     expect(resolved.baseUrl).toBe('http://127.0.0.1:8080/v1')
-    expect(resolved.resolvedModel).toBe('gpt-5.4')
+    expect(resolved.resolvedModel).toBe('gpt-5.5')
   })
 
   test('resolves codexplan to Codex transport even when OPENAI_BASE_URL is the string "undefined"', async () => {
@@ -161,7 +161,7 @@ describe('Codex provider config', () => {
     const resolved = resolveProviderRequest()
     expect(resolved.transport).toBe('codex_responses')
     expect(resolved.baseUrl).toBe('https://chatgpt.com/backend-api/codex')
-    expect(resolved.resolvedModel).toBe('gpt-5.4')
+    expect(resolved.resolvedModel).toBe('gpt-5.5')
   })
 
   test('does not override custom base URL for codexplan (e.g., local provider)', async () => {

src/services/api/providerConfig.ts

@@ -31,7 +31,11 @@ const CODEX_ALIAS_MODELS: Record<
   }
 > = {
   codexplan: {
-    model: 'gpt-5.4',
+    model: 'gpt-5.5',
+    reasoningEffort: 'high',
+  },
+  'gpt-5.5': {
+    model: 'gpt-5.5',
     reasoningEffort: 'high',
   },
   'gpt-5.4': {
@@ -59,6 +63,10 @@ const CODEX_ALIAS_MODELS: Record<
   'gpt-5.1-codex-mini': {
     model: 'gpt-5.1-codex-mini',
   },
+  'gpt-5.5-mini': {
+    model: 'gpt-5.5-mini',
+    reasoningEffort: 'medium',
+  },
   'gpt-5.4-mini': {
     model: 'gpt-5.4-mini',
     reasoningEffort: 'medium',