chore(vocero): remove the legacy ApiPilot integration (#3)

Vocero now retrieves AquaPortal content through authenticated MCP. This removes the obsolete ApiPilot integration from the API and browser while preserving the separately deployed speech pipeline.

Release notes:

- Removed ApiPilot endpoints, configuration, credential overrides, and HTTP/realtime tool execution.
- Removed browser ApiPilot catalog loading and prompt generation while retaining authenticated MCP discovery.
- Updated regression coverage and operating documentation for the retired routes and settings.

Reviewed-on: AquaPortal/s2s#3

AGENTS.md

@@ -43,7 +43,7 @@ URLs, not filesystem paths.
 | `vocero-api/vocero_api/api/`       | HTTP routes, route registration, and response validation helper                             |
 | `vocero-api/vocero_api/models/`    | Pydantic request and response contracts                                                     |
 | `vocero-api/vocero_api/core/`      | Environment parsing, logging, public URLs, and startup diagnostics                          |
-| `vocero-api/vocero_api/providers/` | ApiPilot and caller/profile/report HTTP integrations                                        |
+| `vocero-api/vocero_api/providers/` | Authenticated MCP transport, backend login, and caller/profile/report HTTP integrations     |
 | `vocero-api/vocero_api/services/`  | Prompt/context construction, reasoning, and tool-context rendering                          |
 | `vocero-api/vocero_api/realtime/`  | WebSocket relay, event handling, marker filtering, and audio forwarding                     |
 | `vocero-frontend/`                    | React, TypeScript, Tailwind, and Vite browser application                                   |
@@ -139,7 +139,7 @@ evidence; do not bundle them into tooling or structural refactors.
   migration at `3d42df5`. `vocero-api/tests/test_compatibility.py` compares HTTP
   response bytes, statuses, selected headers, outgoing requests, request schemas,
   and realtime frames. Do not regenerate captures merely to make a refactor pass.
-- Known reasoning failures, ApiPilot authentication/cache quirks, and relay
+- Known reasoning failures and relay
   behavior are documented in the compatibility guide. Preserve narrow lint/type
   exceptions that retain those behaviors until a deliberate fix is in scope.
 - The pytest warning filter is only for Starlette TestClient's exact deprecated