refactor: split tool declarations into domain files + role config UI

tools/__init__.py shrinks from 1,137 → 250 lines. Each domain file now
owns both its callables and its FunctionDeclarations (DECLARATIONS list),
so adding a new tool only touches one file.

New TOOL_CATEGORIES dict exported from __init__ — used by the UI for
grouped tool checkboxes.

Role config UI (Settings → Model Registry → Role Assignments):
- ⚙ button per role expands an inline configure panel
- Textarea for system_append (injected into system prompt for this role)
- Grouped checkboxes for tool allow-list (all checked = no restriction)
- POST /api/models/role-config saves both fields; updates ROLE_CONFIG_DATA
  in-page so re-open reflects current state without a page reload

Backend:
- model_registry.set_role_config() writes system_append + tools to registry
- TOOL_CATEGORIES exported from tools/__init__ for UI rendering
- TOOLS.md header updated: 30 → 39 tools (ae_journal_* and cortex_* additions)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/tools/web.py

@@ -6,6 +6,7 @@ import asyncio
 import logging
 
 import httpx
+from google.genai import types
 
 from config import settings
 
@@ -74,3 +75,41 @@ async def http_fetch(
     except Exception as e:
         logger.warning("http_fetch error for %s: %s", url, e)
         return f"Error: {e}"
+
+
+DECLARATIONS = [
+    types.FunctionDeclaration(
+        name="web_search",
+        description=(
+            "Search the web for current information. Use this when you need up-to-date "
+            "facts, news, documentation, or anything not in your training data."
+        ),
+        parameters=types.Schema(
+            type=types.Type.OBJECT,
+            properties={
+                "query": types.Schema(type=types.Type.STRING, description="The search query string"),
+                "max_results": types.Schema(type=types.Type.INTEGER, description="Number of results to return (default 5, max 10)"),
+            },
+            required=["query"],
+        ),
+    ),
+    types.FunctionDeclaration(
+        name="http_fetch",
+        description=(
+            "Fetch a specific URL and return the response. Unlike web_search, this hits "
+            "a direct URL — useful for health checks, JSON API endpoints, webhook testing, "
+            "or reading a specific page when you already know the URL. "
+            "Response body is capped at 8 KB."
+        ),
+        parameters=types.Schema(
+            type=types.Type.OBJECT,
+            properties={
+                "url": types.Schema(type=types.Type.STRING, description="Full URL to fetch"),
+                "method": types.Schema(type=types.Type.STRING, description="HTTP method: GET (default), POST, HEAD"),
+                "body": types.Schema(type=types.Type.STRING, description="Optional request body (for POST requests)"),
+                "timeout": types.Schema(type=types.Type.INTEGER, description="Request timeout in seconds (default 15, max 60)"),
+            },
+            required=["url"],
+        ),
+    ),
+]