feat(mcp): connect authenticated AquaPortal tools to Vocero (#1)

Vocero needs to query AquaPortal on behalf of the caller selected by the existing phone link. This adds server-owned conversations and MCP tool execution for voice and HTTP reasoning while leaving the speech pipeline unchanged.

Release notes:

- Added browser-bound conversations that keep backend credentials server-side and isolate callers.
- Connected the eight-tool AquaPortal catalog through authenticated Streamable HTTP with full input schemas and structured results.
- Added bounded multi-step tool execution with cancellation, expiry, and stale-result protection.
- Updated browser bootstrap, tool progress, reasoning headers, and conversation cleanup.
- Disabled legacy unscoped content preloads in MCP mode and documented configuration and deployment constraints.
- Preserved disabled-mode contracts and added local SDK, WebSocket, and browser regression coverage.

Reviewed-on: AquaPortal/s2s#1

vocero-api/vocero_api/core/diagnostics.py

@@ -59,3 +59,13 @@ app_logging.logger.info(
     else "-",
 )
 del _STARTUP_APIPILOT_EXEC_URL
+
+if settings.S2S_MCP_URL:
+    app_logging.logger.info(
+        "[STARTUP] AquaPortal MCP enabled: per-caller sessions, legacy content preloads disabled; "
+        "operationTimeout=%ds maxCallsPerTurn=%d conversationTtl=%ds capacity=%d",
+        settings.S2S_MCP_TIMEOUT_SEC,
+        settings.S2S_MCP_MAX_CALLS_PER_TURN,
+        settings.S2S_CONVERSATION_TTL_SEC,
+        settings.S2S_MAX_CONVERSATIONS,
+    )