feat: fix channel scanning bugs, add package tags, and kickstarters tab

Bug fixes:
- Fix channels not being scanned by paginating TDLib getChats (was only
  loading first batch, additional channels were unknown to TDLib)
- Add per-channel getChat pre-load as safety net before scanning
- Fix preview pictures not loading by checking previewData instead of
  previewMsgId for hasPreview flag
- Prevent previewMsgId from being set when preview download fails

Package Tags:
- Add tags Text[] column to Package with migration backfilling from
  channel categories
- Worker auto-inherits source channel category as initial tag
- Tag filter dropdown and Tags column in STL Files table
- Server actions for individual and bulk tag editing

Kickstarters Tab:
- New KickstarterHost, Kickstarter, and KickstarterPackage models
- Full CRUD with delivery status, payment status, host management
- Package linking (many-to-many with existing packages)
- Sidebar entry with Gift icon
- Table with search, filters, modal forms

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/schemas/kickstarter.schema.ts

@@ -0,0 +1,19 @@
+import { z } from "zod/v4";
+
+export const kickstarterSchema = z.object({
+  name: z.string().min(1, "Name is required").max(200),
+  link: z.string().url().optional().or(z.literal("")),
+  filesUrl: z.string().url().optional().or(z.literal("")),
+  deliveryStatus: z.enum(["NOT_DELIVERED", "PARTIAL", "DELIVERED"]),
+  paymentStatus: z.enum(["PAID", "UNPAID"]),
+  hostId: z.string().optional().or(z.literal("")),
+  notes: z.string().max(2000).optional(),
+});
+
+export type KickstarterInput = z.infer<typeof kickstarterSchema>;
+
+export const kickstarterHostSchema = z.object({
+  name: z.string().min(1, "Name is required").max(100),
+});
+
+export type KickstarterHostInput = z.infer<typeof kickstarterHostSchema>;