Settings overhaul + UI polish pass

Two months of iteration on the Settings panel, integration forms, and
small visual nudges across the app. Highlights:

Settings restructure
- Add Models: split into separate Local + API cards (no more in-card
  tabs); each fuses Type/Provider with the URL input.
- Added Models: new dedicated sidebar tab, with Probe + Clear-offline
  pulled into its header; Local/API sub-section icons accent-tinted.
- Search: Web Search and a new Deep Research card (Model + tuning),
  with a cross-link to AI Defaults. Provider hints use real clickable
  anchors; Web Search Test button shows a whirlpool spinner.
- AI Defaults: Image Generation card returns; Research Model card
  carries only Endpoint+Model with a cross-link to Search; Vision /
  Default / Utility fallbacks unified under one numbered-row design
  matching Search's chain.
- API Permissions (was 'API Tokens'): per-row rename, inline
  Permissions toggle that expands the scope-edit panel, in-field
  copy icons (icon→check on success). Empty state accent-tinted.
- Integrations: + Add Integration drops a type-picker menu directly
  under the button (drop-up on tight viewports); each integration
  form (API, CalDAV, CardDAV, Email, Codex/Claude, Vault, MCP) uses
  the same accent-outlined Save/Test/Cancel buttons right-aligned.
- Danger Zone: Wipe→Delete with trash icons; new 'Delete everything'
  row at the bottom that loops every category.

AI Synthesis (Reminders)
- Persona dropdown sourced from PROMPT_TEMPLATES + custom preset.
- src/reminder_personas.py mirrors the five built-ins for the
  server-side synthesis path.
- dispatch_reminder() reads reminder_llm_persona and uses the
  persona's system prompt; empty/unknown falls back to warm-neutral.

Esc handling
- Kebab menus and the provider picker intercept Esc in capture phase
  so dismissing a popup no longer closes the whole Settings modal.

Accent tinting
- Scoped CSS rule across data-settings-panel=ai/services/added-models/
  search/integrations/reminders for card h2 icons + the Added Models
  sub-section icons.

Codex/Claude integration form
- No more auto-creation on form open — explicit Create token button.
- New tokens start with every scope granted; existing tokens move out
  of the integration form into the API Permissions card.
- Setup reveal: copy buttons inline inside the token + setup code
  blocks; shorter subtitle wording.

Misc visual polish
- Save/Test/Cancel uniformly accent-outlined and right-aligned on
  every integration form.
- Provider logos render inline next to the search fallback selects
  and the Deep Research Search dropdown.
- Trash icons in fallback rows bumped to 20x20 so they fill the 32px
  button.
- Image generation default flipped to off.

src/tool_index.py

@@ -94,7 +94,7 @@ BUILTIN_TOOL_DESCRIPTIONS: Dict[str, str] = {
     "manage_mcp": "MCP server management: list, add, delete, reconnect servers, or list available tools.",
     "manage_webhooks": "Webhook management: list, add, delete, enable, or disable webhooks.",
     "manage_tokens": "API token management: list, create, or delete API access tokens.",
-    "manage_documents": "List, read, delete, or tidy documents in the editor panel. action='list' returns clickable rows (most-recent first) so the user can open any doc by clicking. action='read' (aka view/open/get) with document_id returns the content. action='delete' with document_id removes a doc (only way to delete). Use this for ANY 'show/read/list/open my documents/docs/files/notes' request — never shell or curl.",
+    "manage_documents": "List, read, delete, or tidy documents in the editor panel. action='list' returns clickable rows (most-recent first) so the user can open any doc by clicking. action='read' (aka view/open/get) with document_id returns the content; supports offset=<N> + limit=<N> to page through large docs (response includes next_offset when more remains, so you can keep calling with offset=next_offset). action='delete' with document_id removes a doc (only way to delete). Use this for ANY 'show/read/list/open my documents/docs/files/notes' request — never shell or curl.",
     "manage_research": "List, read/open, or delete saved DEEP RESEARCH results from the Library. action='list' returns clickable [query](#research-<id>) rows (most-recent first). action='read' (aka open/view/get) with id returns the report + sources. action='delete' with id removes it. Use this for ANY 'open/read/find/delete my research / that report / the research on X' request. NOTE: this is for EXISTING research; to START new research use trigger_research.",
     "manage_settings": "Change ANY real app setting (the ones the Settings panel writes) so the user never has to open it: TTS voice/provider/speed, STT, search engine + result count, default/teacher/task/utility/vision/image/research models, image quality, reminder channel (browser/email/ntfy), agent timeout/tool-call budget, and more. action=set with key (friendly aliases ok: voice, 'search engine', 'default model', 'teacher model', 'image quality', 'reminder channel'...) + value; get/list/reset too. Also toggles tools on/off (disable_tool/enable_tool/list_tools). Secrets/API keys are read-only. Use for any 'change my…/set my…/use X for…/turn on…' preference request.",
     "create_session": "Create a new chat with a name and model.",