feat(labdb): wire bridge_server to live PostgreSQL via pgrtl

End-to-end PRG → Go RTL → pgxpool → labdb queries → JSON response,
from a single 24 MB binary with no Node.js, FFI, or Apache anywhere
in the request path.

  app/bridge_server.prg:
    Main now opens a pgxpool handle from LABDB_DSN (or the local
    Homebrew default) before HTTP_SERVER_START, then publishes it
    via LABDB_SET_PG so request goroutines can pick it up.

    BridgeDispatch calls FetchRouteData before the per-path PRG
    handler runs. FetchRouteData maps a few /api/* routes to the
    same SQL the upstream server.js endpoint runs, encodes results
    via hb_jsonEncode, and stuffs them into ctx fields under the
    same keys the existing labdb api/*.prg handlers already read
    (rows, total, devices, etc.). PRG handlers stay unmodified.

  hbrtl_ext/labdb_state/:
    Tiny Go RTL that holds the PG handle in a sync/atomic.Int64.
    Picked this over a PRG STATIC/PUBLIC variable to sidestep
    Five's stricter parser (now that parser.go errors on missing
    terminators, anything more elaborate in the entry .prg adds
    friction without buying anything).

Verified against a Homebrew postgres@16 cluster seeded with 2 devices
+ 2 sessions:

  /api/admin-stats.prg
    → {"devices":2,"sessions":2,"records":0,"active_sessions":1}
  /api/sessions-list.prg
    → {"sessions":[...two rows with full fields...],"total":2}
  /api/admin-devices.prg
    → {"devices":[...two rows with api_key/created_at...]}
  /api/hello.prg (no DB)
    → unchanged from 1a.4-3

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/bridge_server.prg

@@ -7,7 +7,19 @@
 // and use AP_METHOD/AP_BODY/AP_JSONRESPONSE/ctx_get/... freely.
 
 FUNCTION Main()
-   LOCAL cErr := HTTP_SERVER_START( ":8090", "BRIDGEDISPATCH" )
+   LOCAL cDsn := hb_GetEnv( "LABDB_DSN", "postgres://" + hb_GetEnv( "USER", "" ) + "@127.0.0.1:5432/labdb?sslmode=disable" )
+   LOCAL nH, cErr
+
+   ? "labdb: opening PG", cDsn
+   nH := PG_OPEN( cDsn )
+   IF nH < 0
+      ? "labdb: PG_OPEN failed (handlers will see empty ctx — server still starts)"
+   ELSE
+      ? "labdb: PG handle =", nH
+   ENDIF
+   LABDB_SET_PG( nH )
+
+   cErr := HTTP_SERVER_START( ":8090", "BRIDGEDISPATCH" )
    IF cErr != NIL
       ? "httpserver:", cErr
    ENDIF
@@ -26,6 +38,8 @@ FUNCTION BridgeDispatch( hReq )
       "headers_out"  => { => }, ;
       "status"       => 200 ;
    }
+   FetchRouteData( hReq[ "path" ], hCtx )
+
    _CTX_SET_JSON( hb_jsonEncode( hCtx ) )
    _OUT_CLEAR()
 
@@ -52,6 +66,45 @@ FUNCTION BridgeDispatch( hReq )
       "body"    => _OUT_GET() ;
    }
 
+// FetchRouteData runs the per-route SQL the matching server.js endpoint
+// would have run and drops the values into ctx fields the corresponding
+// PRG handler reads via ctx_get(). Routes without a SQL block here fall
+// through to whatever default the handler uses (which is what 1a.4-3
+// validated). Extend by adding cases as more endpoints come online.
+FUNCTION FetchRouteData( cPath, hCtx )
+   LOCAL aRows
+   LOCAL nPG := LABDB_GET_PG()
+
+   IF nPG < 0
+      RETURN NIL
+   ENDIF
+
+   DO CASE
+   CASE cPath == "/api/admin-stats.prg" .OR. cPath == "/api/admin-stats"
+      aRows := PG_QUERY( nPG, "SELECT (SELECT COUNT(*) FROM devices) AS devices, (SELECT COUNT(*) FROM sessions) AS sessions, (SELECT COUNT(*) FROM records) AS records, (SELECT COUNT(*) FROM sessions WHERE status = 'active') AS active_sessions" )
+      IF aRows != NIL .AND. Len( aRows ) > 0
+         hCtx[ "devices" ]         := hb_NToS( aRows[ 1 ][ "devices" ] )
+         hCtx[ "sessions" ]        := hb_NToS( aRows[ 1 ][ "sessions" ] )
+         hCtx[ "records" ]         := hb_NToS( aRows[ 1 ][ "records" ] )
+         hCtx[ "active_sessions" ] := hb_NToS( aRows[ 1 ][ "active_sessions" ] )
+      ENDIF
+
+   CASE cPath == "/api/sessions-list.prg" .OR. cPath == "/api/sessions-list"
+      aRows := PG_QUERY( nPG, "SELECT session_id, device_id, session_name, start_time, end_time, record_count, status FROM sessions ORDER BY start_time DESC LIMIT 50" )
+      IF aRows != NIL
+         // sessions-list.prg reads ctx_get("rows", "[]")
+         hCtx[ "rows" ]  := hb_jsonEncode( aRows )
+         hCtx[ "total" ] := hb_NToS( Len( aRows ) )
+      ENDIF
+
+   CASE cPath == "/api/admin-devices.prg" .OR. cPath == "/api/admin-devices"
+      aRows := PG_QUERY( nPG, "SELECT device_id, device_name, api_key, is_active, created_at FROM devices ORDER BY created_at DESC" )
+      IF aRows != NIL
+         hCtx[ "rows" ] := hb_jsonEncode( aRows )
+      ENDIF
+   ENDCASE
+RETURN NIL
+
 // /api/admin-stats.prg  -> ADMIN_STATS__MAIN
 // /api/hello.prg        -> HELLO__MAIN
 // /api/hello            -> HELLO__MAIN (extension optional)