feat: security hardening, DB indexes, token revocation, and input validation

- SSRF protection: DNS resolution + private IP blocking on metadata fetcher
- Upload security: CSP/X-Frame-Options headers, SVG forced download, nosniff
- Auth hardening: JWT secret min length, password min 8 chars, token revocation via password_changed_at
- Attachment ownership verification before linking to messages
- Message length limit (4000 chars) enforced on client and server
- Asset URL validation on avatar/banner updates
- Federation instance validation (domain regex, origin scheme, length limits)
- DB indexes on all FK columns for query performance
- Migrations: nullable moderator columns, dm_messages reply_to FK constraint
- File cleanup on avatar/banner replacement and space deletion
- Fastify trustProxy, AbortController on fetches, typing map size cap

packages/server/src/routes/admin.ts

@@ -188,7 +188,7 @@ export async function adminRoutes(app: FastifyInstance): Promise<void> {
       const hash = await hashPassword(temporaryPassword);
 
       db.update(schema.users)
-        .set({ passwordHash: hash })
+        .set({ passwordHash: hash, passwordChangedAt: Date.now() })
         .where(eq(schema.users.id, targetId))
         .run();