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/components/ProviderForm.codexCatalog.test.ts

@@ -0,0 +1,18 @@
+import { describe, expect, it } from "vitest";
+import { normalizeCodexCatalogModelsForSave } from "@/components/providers/forms/ProviderForm";
+
+describe("ProviderForm Codex catalog helpers", () => {
+  it("normalizes catalog rows and removes empty or duplicate models", () => {
+    expect(
+      normalizeCodexCatalogModelsForSave([
+        { model: " deepseek-v4-flash ", displayName: " DeepSeek " },
+        { model: "deepseek-v4-flash", displayName: "Duplicate" },
+        { model: "", displayName: "Empty" },
+        { model: "kimi-k2", contextWindow: "128000 tokens" },
+      ]),
+    ).toEqual([
+      { model: "deepseek-v4-flash", displayName: "DeepSeek" },
+      { model: "kimi-k2", contextWindow: 128000 },
+    ]);
+  });
+});