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_implementations.py

@@ -1436,9 +1436,25 @@ async def do_manage_documents(content: str, owner: Optional[str] = None) -> Dict
             if not doc:
                 return {"error": f"Document '{doc_id}' not found", "exit_code": 1}
             body = doc.current_content or ""
+            total = len(body)
+            # Clamp offset to [0, total] so a far-out offset returns an empty
+            # window with a useful "end of document" hint rather than erroring.
+            try: offset = int(args.get("offset", 0))
+            except (TypeError, ValueError): offset = 0
+            offset = max(0, min(offset, total))
             preview_limit = int(args.get("limit", MAX_READ_CHARS))
-            truncated = len(body) > preview_limit
-            preview = body[:preview_limit] + (f"\n... (truncated, {len(body)} chars total)" if truncated else "")
+            chunk = body[offset:offset + preview_limit]
+            next_offset = offset + len(chunk)
+            has_more = next_offset < total
+            # Trailing marker — tells the agent (and a curious human) exactly
+            # what to pass next to continue paginating.
+            if has_more:
+                marker = f"\n... ({total - next_offset:,} more chars; pass offset={next_offset} to continue)"
+            elif offset > 0:
+                marker = f"\n... (end of document, {total:,} chars total)"
+            else:
+                marker = ""
+            preview = chunk + marker
             anchor = f"[{doc.title}](#document-{doc.id})"
             return {
                 "response": f"{anchor} — click to open in editor.\n\n```{doc.language or ''}\n{preview}\n```",
@@ -1446,9 +1462,11 @@ async def do_manage_documents(content: str, owner: Optional[str] = None) -> Dict
                     "id": doc.id,
                     "title": doc.title,
                     "language": doc.language,
-                    "size": len(body),
-                    "content": preview,
-                    "truncated": truncated,
+                    "size": total,
+                    "content": chunk,
+                    "offset": offset,
+                    "next_offset": next_offset if has_more else None,
+                    "truncated": has_more,
                 },
                 "exit_code": 0,
             }