Replace seenByTenant boolean with seenByTenantAt timestamp field

Update location tracking to record when tenant views a location rather than just whether they've seen it. This provides better audit trail and enables future features like viewing history.

Changes:
- Convert seenByTenant (boolean) to seenByTenantAt (Date) in database schema
- Update setSeenByTenantAt action to store timestamp instead of boolean flag
- Modify LocationCard UI to display when location was seen by tenant
- Update all references across locationActions, monthActions, and view components
- Remove unused imports from ViewLocationCard

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/lib/actions/locationActions.ts

@@ -428,7 +428,7 @@ export const fetchAllLocations = withUser(async (user:AuthenticatedUser, year:nu
                     "yearMonth.year": 1,
                     "yearMonth.month": 1,
                     "bills": 1,
-                    "seenByTenant": 1,
+                    "seenByTenantAt": 1,
                     // "bills.attachment": 0,
                     // "bills.notes": 0,
                     // "bills.hub3aText": 1,
@@ -555,7 +555,7 @@ export const deleteLocationById = withUser(async (user:AuthenticatedUser, locati
 })
 
 /**
- * Sets the `seenByTenant` flag to true for a specific location.
+ * Sets the `seenByTenantAt` flag to true for a specific location.
  *
  * This function marks a location as viewed by the tenant. It first checks if the flag
  * is already set to true to avoid unnecessary database updates.
@@ -564,17 +564,17 @@ export const deleteLocationById = withUser(async (user:AuthenticatedUser, locati
  * @returns {Promise<void>}
  *
  * @example
- * await setSeenByTenant("507f1f77bcf86cd799439011");
+ * await setseenByTenantAt("507f1f77bcf86cd799439011");
  */
-export const setSeenByTenant = async (locationID: string): Promise<void> => {
+export const setSeenByTenantAt = async (locationID: string): Promise<void> => {
     const dbClient = await getDbClient();
 
-    // First check if the location exists and if seenByTenant is already true
+    // First check if the location exists and if seenByTenantAt is already true
     const location = await dbClient.collection<BillingLocation>("lokacije")
         .findOne({ _id: locationID });
 
-    // If location doesn't exist or seenByTenant is already true, no update needed
-    if (!location || location.seenByTenant === true) {
+    // If location doesn't exist or seenByTenantAt is already true, no update needed
+    if (!location || location.seenByTenantAt) {
         return;
     }
 
@@ -582,7 +582,7 @@ export const setSeenByTenant = async (locationID: string): Promise<void> => {
     await dbClient.collection<BillingLocation>("lokacije")
         .updateOne(
             { _id: locationID },
-            { $set: { seenByTenant: true } }
+            { $set: { seenByTenantAt: new Date() } }
         );
 }
 

app/lib/actions/monthActions.ts

@@ -40,7 +40,7 @@ export const addMonth = withUser(async (user:AuthenticatedUser, { year, month }:
             // copy all the properties from the previous location
             ...prevLocation,
             // clear properties specific to the month
-            seenByTenant: undefined,
+            seenByTenantAt: undefined,
             utilBillsProofOfPaymentUploadedAt: undefined,
             utilBillsProofOfPaymentAttachment: undefined,
             // assign a new ID