refactor: replace focusedIndex with activeChildId

- Replace focusedIndex integer with activeChildId string in messages schema
- Add migration to convert existing data and drop focused_index column
- Add  hooks for providers.updatedAt and messageParts.lastUpdatedAt
- Add file size column to files table
- Update message navigation to use child ID-based lookup
- Simplify delete logic by removing focusedIndex math
- Fix file delete endpoint filename ([id[ -> [id])

server/api/topic/[topicId]/chat/index.post.ts

@@ -260,8 +260,8 @@ export default defineEventHandler(async (event) => {
             });
         }
 
-        await db.update(messages).set({ focusedIndex: (parentMessage.focusedIndex ?? 0) + 1 }).where(eq(messages.id, parentMessageId));
-        events.push({ type: 'MESSAGE_UPDATED', payload: { focusedIndex: (parentMessage.focusedIndex ?? 0) + 1 } });
+        await db.update(messages).set({ activeChildId: agentmessage.id }).where(eq(messages.id, parentMessageId));
+        events.push({ type: 'MESSAGE_UPDATED', payload: { id: parentMessageId, activeChildId: agentmessage.id } });
 
         // we need to make the topic messages all the messages excluding the ones after the message we wish to regenerate
         // and if parentMessageId is undefined, then excluding the last message
@@ -392,7 +392,13 @@ type SearchTheWebConfig = SearchTheWebRerankedConfig | SearchTheWebUnrankedConfi
 
 export const searchTheWeb = (config: SearchTheWebConfig) => {
     return async (query: string) => {
-        const results = await $fetch<any>(`${process.env.SEARXNG_URL}/search`, {
+        const results = await $fetch<{
+            results: Array<{
+                title: string;
+                url: string;
+                content: string;
+            }>;
+        }>(`${process.env.SEARXNG_URL}/search`, {
             query: {
                 q: query,
                 format: 'json',
@@ -675,6 +681,7 @@ async function generateResponse(
                     payload: {
                         messageId: message.id,
                         partId: part.id,
+                        lastUpdatedAt: new Date(),
                         content: part.accumulatedContent,
                     }
                 })
@@ -850,6 +857,7 @@ async function generateResponse(
                             payload: {
                                 messageId: message.id,
                                 partId: part.id,
+                                lastUpdatedAt: new Date(),
                                 content: token.text,
                             }
                         })
@@ -903,6 +911,7 @@ async function generateResponse(
                             payload: {
                                 messageId: message.id,
                                 partId: part.id,
+                                lastUpdatedAt: dbPart.lastUpdatedAt,
                                 content: part.accumulatedContent,
                             }
                         })
@@ -1177,7 +1186,7 @@ async function generateResponse(
                                 error: {
                                     type: outputType as ToolCallType,
                                     value: outputValue as string,
-                                }
+                                },
                             }
                         })
                     } else {