Migrate frontend to Svelte 5 runes semantics

frontend/src/components/MissingMappingModal.svelte

@@ -3,36 +3,34 @@
 @SEMANTICS: modal, mapping, prompt, migration
 @PURPOSE:   Prompts the user to provide a database mapping when one is missing during migration.
 @LAYER:     Feature
-@RELATION:  DISPATCHES -> resolve
+@RELATION:  BINDS_TO -> onresolve
+@RELATION:  BINDS_TO -> oncancel
 
 @INVARIANT: Modal blocks migration progress until resolved or cancelled.
 -->
 
 <script lang="ts">
-  // [SECTION: IMPORTS]
-  import { createEventDispatcher } from 'svelte';
-  // [/SECTION]
-
   // [SECTION: PROPS]
   let {
     show = false,
     sourceDbName = "",
     sourceDbUuid = "",
     targetDatabases = [],
+    onresolve = () => {},
+    oncancel = () => {},
   } = $props();
 
   // [/SECTION]
 
   let selectedTargetUuid = $state("");
-  const dispatch = createEventDispatcher();
 
   // [DEF:resolve:Function]
-  // @PURPOSE: Dispatches the resolution event with the selected mapping.
+  // @PURPOSE: Resolves the missing mapping via callback prop.
   // @PRE: selectedTargetUuid must be set.
-  // @POST: 'resolve' event is dispatched and modal is hidden.
+  // @POST: Parent callback receives mapping payload and modal closes.
   function resolve() {
     if (!selectedTargetUuid) return;
-    dispatch('resolve', {
+    onresolve({
       sourceDbUuid,
       targetDbUuid: selectedTargetUuid,
       targetDbName: targetDatabases.find(d => d.uuid === selectedTargetUuid)?.database_name
@@ -44,9 +42,9 @@
   // [DEF:cancel:Function]
   // @PURPOSE: Cancels the mapping resolution modal.
   // @PRE: Modal is open.
-  // @POST: 'cancel' event is dispatched and modal is hidden.
+  // @POST: Parent cancel callback is invoked and modal is hidden.
   function cancel() {
-    dispatch('cancel');
+    oncancel();
     show = false;
   }
   // [/DEF:cancel:Function]