fix: Codex model catalog WYSIWYG and config consolidation

- Remove mergeCodexDefaultCatalogModelForSave implicit injection (P1)
  The model mapping table is now the single source of truth; no hidden
  entries are prepended on save.

- Sync first catalog row model into config.toml on save
  Ensures Codex default request model matches the table's first entry
  instead of retaining a stale template value.

- Remove API Format selector from CodexFormFields (P3)
  wire_api is always 'responses'; the selector confused users into
  thinking they were changing the upstream protocol. Only the 'Needs
  Local Routing' toggle remains.

- Add restart hint to model mapping i18n text (P2)
  model_catalog_json is loaded at Codex startup; users are now informed
  that a restart is needed after changes.

- Unify write_codex_live_with_catalog helper (P4)
  Replaces three scattered prepare+write call sites in config.rs,
  provider/live.rs, and proxy.rs with a single entry point.

- Clean up useCodexConfigState dead state (P3 follow-up)
  Remove codexModelName, codexContextWindow, codexAutoCompactLimit and
  their handlers/effects since no component consumes them after the UI
  consolidation.

tests/utils/providerConfigUtils.codex.test.ts

@@ -2,8 +2,11 @@ import { describe, expect, it } from "vitest";
 import {
   extractCodexBaseUrl,
   extractCodexModelName,
+  extractCodexTopLevelInt,
+  removeCodexTopLevelField,
   setCodexBaseUrl,
   setCodexModelName,
+  setCodexTopLevelInt,
 } from "@/utils/providerConfigUtils";
 
 describe("Codex TOML utils", () => {
@@ -148,4 +151,50 @@ describe("Codex TOML utils", () => {
     expect(extractCodexBaseUrl(input)).toBe("https://api.example.com/v1");
     expect(extractCodexModelName(input)).toBe("gpt-5");
   });
+
+  it("reads, writes, and removes top-level integer metadata fields", () => {
+    const input = [
+      'model_provider = "custom"',
+      'model = "deepseek-v4-flash"',
+      "",
+      "[model_providers.custom]",
+      'name = "DeepSeek"',
+      "",
+    ].join("\n");
+
+    const withContext = setCodexTopLevelInt(
+      input,
+      "model_context_window",
+      128000,
+    );
+    const withCompact = setCodexTopLevelInt(
+      withContext,
+      "model_auto_compact_token_limit",
+      90000,
+    );
+
+    expect(extractCodexTopLevelInt(withCompact, "model_context_window")).toBe(
+      128000,
+    );
+    expect(
+      extractCodexTopLevelInt(
+        withCompact,
+        "model_auto_compact_token_limit",
+      ),
+    ).toBe(90000);
+    expect(withCompact).toMatch(/^model_context_window = 128000$/m);
+    expect(withCompact).toMatch(
+      /^model_auto_compact_token_limit = 90000$/m,
+    );
+
+    const removed = removeCodexTopLevelField(
+      withCompact,
+      "model_context_window",
+    );
+
+    expect(
+      extractCodexTopLevelInt(removed, "model_context_window"),
+    ).toBeUndefined();
+    expect(removed).toContain("[model_providers.custom]");
+  });
 });