feat(server): integrate MCP queries and investigation messaging

Add project-bound OAuth MCP queries and controlled analysis with scoped evidence,
limits, timeouts and a nearby-model spatial query using EPSG:4326 inputs.
Default nearby searches to 200 meters and five results.

Integrate investigation messaging/presentation, health/readiness and typed history;
remove duplicate web search and fix online simulation and compressed baseline writes.
Include project migrations 023-025; keep local credentials and demo seeding excluded.

Validation: 319 focused pytest checks; real PostGIS temporary-table regression;
read-only Jinqian bridge radius comparison; cross-language MCP discovery/calls.

app/api/health.py

@@ -0,0 +1,58 @@
+"""Public process probes, separate from authenticated project diagnostics."""
+
+import asyncio
+
+from fastapi import APIRouter, Request
+from fastapi.responses import JSONResponse
+from sqlalchemy import text
+
+from app.infra.db.metadb.database import engine
+
+
+router = APIRouter(include_in_schema=False)
+METADATA_TIMEOUT_SECONDS = 2
+
+
+async def metadata_database_ready() -> bool:
+    try:
+        async with asyncio.timeout(METADATA_TIMEOUT_SECONDS):
+            async with engine.connect() as connection:
+                result = await connection.execute(text("SELECT 1"))
+                return result.scalar_one() == 1
+    except Exception:
+        # Public probes must not expose connection strings or driver errors.
+        return False
+
+
+@router.get("/health")
+async def health() -> dict[str, str]:
+    """Check HTTP liveness without project or database dependencies."""
+    return {"status": "ok"}
+
+
+@router.get("/ready")
+async def readiness(request: Request) -> JSONResponse:
+    """Check startup, metadata connectivity and the enabled MCP lifecycle."""
+    started = getattr(request.app.state, "startup_complete", False)
+    runtime = getattr(request.app.state, "mcp_runtime", None)
+    mcp_ready = runtime is None or runtime.ready
+    metadata_ready = await metadata_database_ready() if started else False
+    ready = started and metadata_ready and mcp_ready
+    return JSONResponse(
+        status_code=200 if ready else 503,
+        content={
+            "status": "ready" if ready else "not_ready",
+            "checks": {
+                "startup": "ready" if started else "not_ready",
+                "metadata_database": (
+                    "not_checked" if not started
+                    else "ready" if metadata_ready else "unavailable"
+                ),
+                "mcp_transport": (
+                    "disabled" if runtime is None
+                    else "ready" if mcp_ready else "not_ready"
+                ),
+            },
+        },
+        headers={"Cache-Control": "no-store"},
+    )