feat: mount MCP server, add bearer auth, and guard outbound calls

The MCP server was created but never mounted — no client could reach
it. Mount it at /mcp/ over streamable HTTP with a combined lifespan,
resolving the gateway lazily so mounting happens at app construction.

Security and safety for the agent surface:
- One static API_TOKEN (SecretStr) enforced across REST (dependency),
  WebSocket (query param/header before accept), and MCP
  (StaticTokenVerifier). Startup refuses tokenless non-loopback binds.
- Emergency numbers (911/9911/112) always refused on make_call, plus a
  MAX_CONCURRENT_CALLS cap; ValueError surfaces as 400/ToolError.
- Safe defaults: debug off, no credential in default DATABASE_URL,
  SIP/LLM/TTS secrets as SecretStr.

Cleanups:
- Delete broken learn_call_flow tool (wrong ctor args, nonexistent
  method) and the never-fed CallAnalytics service; keep
  call_flow_learner for proper wiring later.
- Trim dial_plan to what is actually used (emergency guard, extension
  allocation); delete the unreferenced matcher/normaliser.
- Register call_history before calls so /api/calls/history is no
  longer shadowed by /api/calls/{call_id}.
- fastmcp pinned >=3.0 (http_app + StaticTokenVerifier).

New tests: MCP in-memory client (tool surface, lazy gateway, emergency
refusal, call cap) and API security (401 paths, route order, mount).

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

api/deps.py

@@ -2,11 +2,12 @@
 API Dependencies — Shared dependency injection for all routes.
 """
 
-from fastapi import Depends, HTTPException, Request
-from sqlalchemy.ext.asyncio import AsyncSession
+import secrets
 
+from fastapi import Header, HTTPException, Request
+
+from config import get_settings
 from core.gateway import AIPSTNGateway
-from db.database import get_db
 
 
 def get_gateway(request: Request) -> AIPSTNGateway:
@@ -15,3 +16,24 @@ def get_gateway(request: Request) -> AIPSTNGateway:
     if gateway is None:
         raise HTTPException(status_code=503, detail="Gateway not initialized")
     return gateway
+
+
+def require_token(authorization: str | None = Header(default=None)) -> None:
+    """
+    Enforce the static bearer token (API_TOKEN) on REST routes.
+
+    An empty configured token disables auth; startup refuses that
+    combination unless the server is bound to loopback.
+    """
+    token = get_settings().api_token.get_secret_value()
+    if not token:
+        return
+    supplied = ""
+    if authorization and authorization.lower().startswith("bearer "):
+        supplied = authorization[7:]
+    if not secrets.compare_digest(supplied, token):
+        raise HTTPException(
+            status_code=401,
+            detail="Missing or invalid bearer token",
+            headers={"WWW-Authenticate": "Bearer"},
+        )