feat: add /debug-fb/diagnosticos endpoint to list CIE-10 from Firebird

Supports ?q=filter and ?limit=N. Returns total count, column names,
and list of {cod, concepto} rows — used to plan DIAGNOSTICO migration.

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

app/routes/debug_fb.py

@@ -1,5 +1,5 @@
 import traceback
-from fastapi import APIRouter, Request, Depends
+from fastapi import APIRouter, Request, Depends, Query
 from fastapi.responses import JSONResponse
 from app.database import get_connection
 from app.auth import get_current_user
@@ -8,6 +8,65 @@ from app.services.firebird_service import get_firebird_from_config
 router = APIRouter(prefix="/debug-fb", tags=["debug"])
 
 
+@router.get("/diagnosticos")
+async def listar_diagnosticos(
+    q: str = Query(default="", description="Filtro por código o concepto"),
+    limit: int = Query(default=100, ge=1, le=5000),
+    user: dict = Depends(get_current_user),
+):
+    """Lista diagnósticos CIE-10 desde Firebird DIAGNOSTICO."""
+    try:
+        conn = get_connection()
+        cfg = {r["key"]: r["value"] for r in conn.execute("SELECT * FROM config").fetchall()}
+        conn.close()
+
+        fb, ok, msg = get_firebird_from_config(cfg)
+        if not ok:
+            return JSONResponse({"ok": False, "error": msg})
+
+        # Estructura de la tabla
+        ok_c, _, cols = fb.execute_query(
+            "SELECT TRIM(f.RDB$FIELD_NAME) AS col "
+            "FROM RDB$RELATION_FIELDS f "
+            "WHERE TRIM(f.RDB$RELATION_NAME) = 'DIAGNOSTICO' "
+            "ORDER BY f.RDB$FIELD_POSITION", None
+        )
+
+        # Conteo total
+        ok_n, _, cnt = fb.execute_query(
+            "SELECT COUNT(*) AS TOTAL FROM DIAGNOSTICO", None
+        )
+
+        # Registros
+        if q:
+            q_up = q.upper()
+            ok_r, _, rows = fb.execute_query(
+                f"SELECT FIRST {limit} TRIM(d.COD_DIAG) AS cod, TRIM(d.CONCEPTO) AS concepto "
+                f"FROM DIAGNOSTICO d "
+                f"WHERE UPPER(TRIM(d.COD_DIAG)) CONTAINING '{q_up}' "
+                f"   OR UPPER(TRIM(d.CONCEPTO)) CONTAINING '{q_up}' "
+                f"ORDER BY d.COD_DIAG", None
+            )
+        else:
+            ok_r, _, rows = fb.execute_query(
+                f"SELECT FIRST {limit} TRIM(d.COD_DIAG) AS cod, TRIM(d.CONCEPTO) AS concepto "
+                f"FROM DIAGNOSTICO d ORDER BY d.COD_DIAG", None
+            )
+
+        fb.disconnect()
+
+        return JSONResponse({
+            "ok":      True,
+            "total":   cnt[0]["TOTAL"] if ok_n and cnt else "?",
+            "columnas": [c["col"] for c in cols] if ok_c and cols else [],
+            "limite":  limit,
+            "filtro":  q or None,
+            "rows":    [{"cod": r["cod"], "concepto": r["concepto"]} for r in (rows or [])],
+        })
+    except Exception:
+        return JSONResponse({"ok": False, "traceback": traceback.format_exc()})
+
+
 @router.get("/recepcion")
 async def debug_recepcion(user: dict = Depends(get_current_user)):
     """Diagnóstico: qué hay en RECEPCION hoy sin filtros restrictivos."""