fix: zoom no longer resets after manual pan/zoom (fitBounds once per siruta)

The fitBounds effect was re-triggered every time mapReady toggled
(which happened frequently due to the source-checking polling interval).
Now uses boundsFittedForSirutaRef to ensure fitBounds runs only ONCE
per siruta selection — changing UAT still zooms correctly, but manual
zoom/pan is preserved afterwards.

Fixed in both ParcelSync Harta tab and Portal map.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/modules/parcel-sync/components/tabs/map-tab.tsx

@@ -102,6 +102,7 @@ export function MapTab({ siruta, sirutaValid, sessionConnected, syncLocalCount,
   const appliedSirutaRef = useRef("");
   const boundsRef = useRef<[number, number, number, number] | null>(null);
   const prevCheckSirutaRef = useRef("");
+  const boundsFittedForSirutaRef = useRef("");
 
   /* Boundary check results */
   const [mismatchSummary, setMismatchSummary] = useState<{
@@ -164,12 +165,14 @@ export function MapTab({ siruta, sirutaValid, sessionConnected, syncLocalCount,
           if (data?.bounds) {
             const [[minLng, minLat], [maxLng, maxLat]] = data.bounds;
             boundsRef.current = [minLng, minLat, maxLng, maxLat];
+            boundsFittedForSirutaRef.current = ""; // reset — need to fit for new siruta
             const map = asMap(mapHandleRef.current);
             if (map) {
               map.fitBounds([minLng, minLat, maxLng, maxLat], {
                 padding: 40,
                 duration: 1500,
               });
+              boundsFittedForSirutaRef.current = siruta;
             }
           }
         },
@@ -178,13 +181,16 @@ export function MapTab({ siruta, sirutaValid, sessionConnected, syncLocalCount,
       .finally(() => setBoundsLoading(false));
   }, [siruta, sirutaValid]);
 
-  /* ── When map becomes ready, fitBounds if we have bounds ───── */
+  /* ── When map becomes ready, fitBounds ONCE per siruta ──────── */
   useEffect(() => {
-    if (!mapReady || !boundsRef.current) return;
+    if (!mapReady || !boundsRef.current || !siruta) return;
+    // Only fit bounds once per siruta — don't reset zoom on basemap switch or re-render
+    if (boundsFittedForSirutaRef.current === siruta) return;
     const map = asMap(mapHandleRef.current);
     if (!map) return;
     map.fitBounds(boundsRef.current, { padding: 40, duration: 1500 });
-  }, [mapReady]);
+    boundsFittedForSirutaRef.current = siruta;
+  }, [mapReady, siruta]);
 
   /* ── Apply siruta filter + enrichment overlay ──────────────── */
   useEffect(() => {