fix: Resolve database migration issues and consolidate 003 migrations

- Fix $getActiveIdentity() logic flow preventing false "empty table" warnings
- Implement auto-selection of first account when activeDid is null after migration
- Consolidate 003 and 003b migrations into single 003 migration
- Re-introduce foreign key constraint for activeDid referential integrity
- Add comprehensive debug logging for migration troubleshooting
- Remove 003b validation logic and update migration name mapping

Fixes migration from master to active_did_redux branch and ensures system
always has valid activeDid for proper functionality.

src/utils/PlatformServiceMixin.ts

@@ -668,6 +668,42 @@ export const PlatformServiceMixin = {
             { activeDid },
           );
 
+          // Handle null activeDid (initial state after migration)
+          if (activeDid === null) {
+            logger.debug(
+              "[PlatformServiceMixin] Active identity is null (initial state), attempting auto-selection",
+            );
+            
+            // Try to auto-select first available account
+            const availableAccounts = await this.$dbQuery(
+              "SELECT did FROM accounts ORDER BY dateCreated, did LIMIT 1",
+            );
+            
+            if (availableAccounts?.values?.length) {
+              const firstAccountDid = availableAccounts.values[0][0] as string;
+              logger.debug(
+                "[PlatformServiceMixin] Auto-selecting first account as active:",
+                { firstAccountDid },
+              );
+              
+              // Update active_identity table with the first account
+              await this.$dbExec(
+                "UPDATE active_identity SET activeDid = ?, lastUpdated = datetime('now') WHERE id = 1",
+                [firstAccountDid],
+              );
+              
+              logger.debug(
+                "[PlatformServiceMixin] Active identity auto-selected successfully",
+              );
+              return { activeDid: firstAccountDid };
+            } else {
+              logger.warn(
+                "[PlatformServiceMixin] No accounts available for auto-selection",
+              );
+              return { activeDid: "" };
+            }
+          }
+
           // Validate activeDid exists in accounts
           if (activeDid) {
             const accountExists = await this.$dbQuery(
@@ -690,6 +726,12 @@ export const PlatformServiceMixin = {
               );
               return { activeDid: "" };
             }
+          } else {
+            // activeDid is empty string, return it
+            logger.debug(
+              "[PlatformServiceMixin] Active identity is empty string, returning as-is",
+            );
+            return { activeDid: "" };
           }
         }