feat: chatbot model setting + tool-calling toggle, simplify admin AI config (v0.59.0)

Chatbot (general assistant + per-recipe Q&A) now resolves its default model
from its own site setting (DEFAULT_CHAT_PROVIDER/MODEL) instead of sharing
the generic "text" use case with recipe generation, so admins can point it
at a different model.

Added AI_TOOL_CALLING_ENABLED: turns off the chatbot's createRecipe/
addToShoppingList tools (and the forced-retry pass) for models that don't
reliably support tool calling — it falls back to plain text answers.

Simplified the admin AI Configuration page: it showed provider keys and
routing settings twice (a read-only card, then an identical edit form).
Merged into one editable section; the resolved fallback provider is now a
one-line note instead of its own card.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/lib/changelog.ts

@@ -1,5 +1,5 @@
 // Mirrors CHANGELOG.md at the repo root — update both together.
-export const APP_VERSION = "0.58.0";
+export const APP_VERSION = "0.59.0";
 
 export type ChangelogEntry = {
   version: string;
@@ -11,6 +11,17 @@ export type ChangelogEntry = {
 };
 
 export const CHANGELOG: ChangelogEntry[] = [
+  {
+    version: "0.59.0",
+    date: "2026-07-20 21:15",
+    added: [
+      "Admin: chatbot now has its own default-model setting, separate from generic text generation — the general assistant and per-recipe Q&A chat can be pointed at a different model than recipe generation.",
+      "Admin: tool calling (the chatbot's inline recipe/shopping-list drafting) can be toggled off — useful for a local/Ollama model that doesn't reliably support it, so the bot falls back to plain text answers instead.",
+    ],
+    fixed: [
+      "Simplified the admin AI Configuration page — it showed the same provider keys and routing settings twice (once read-only, once as an edit form). Merged into one section.",
+    ],
+  },
   {
     version: "0.58.0",
     date: "2026-07-20 21:00",