refactor(frontend): extract logic to hooks, split inline components

Area 1 (tv/page.tsx 964→423 lines):
- hooks: use-fullscreen, use-idle, use-volume, use-quality, use-subtitles,
  use-channel-input, use-channel-passwords, use-tv-keyboard
- components: SubtitlePicker, VolumeControl, QualityPicker, TopControlBar,
  LogoWatermark, AutoplayPrompt, ChannelNumberOverlay, TvBaseLayer

Area 2 (edit-channel-sheet.tsx 1244→678 lines):
- hooks: use-channel-form (all form state + reset logic)
- lib/schemas.ts: extracted Zod schemas + extractErrors
- components: AlgorithmicFilterEditor, RecyclePolicyEditor, WebhookEditor,
  AccessSettingsEditor, LogoEditor

Area 3 (dashboard/page.tsx 406→261 lines):
- hooks: use-channel-order, use-import-channel, use-regenerate-all
- lib/channel-export.ts: pure export utility
- components: DashboardHeader

k-tv-frontend/lib/schemas.ts

@@ -0,0 +1,79 @@
+import { z } from "zod";
+
+export const mediaFilterSchema = z.object({
+  content_type: z.enum(["movie", "episode", "short"]).nullable().optional(),
+  genres: z.array(z.string()),
+  decade: z
+    .number()
+    .int()
+    .min(1900, "Decade must be ≥ 1900")
+    .max(2099, "Decade must be ≤ 2090")
+    .nullable()
+    .optional(),
+  tags: z.array(z.string()),
+  min_duration_secs: z.number().min(0, "Must be ≥ 0").nullable().optional(),
+  max_duration_secs: z.number().min(0, "Must be ≥ 0").nullable().optional(),
+  collections: z.array(z.string()),
+  series_names: z.array(z.string()),
+  search_term: z.string().nullable().optional(),
+});
+
+export const accessModeSchema = z.enum([
+  "public",
+  "password_protected",
+  "account_required",
+  "owner_only",
+]);
+
+export const blockSchema = z.object({
+  id: z.string(),
+  name: z.string().min(1, "Block name is required"),
+  start_time: z.string(),
+  duration_mins: z.number().int().min(1, "Must be at least 1 minute"),
+  content: z.discriminatedUnion("type", [
+    z.object({
+      type: z.literal("algorithmic"),
+      filter: mediaFilterSchema,
+      strategy: z.enum(["best_fit", "sequential", "random"]),
+      provider_id: z.string().optional(),
+    }),
+    z.object({
+      type: z.literal("manual"),
+      items: z.array(z.string()),
+      provider_id: z.string().optional(),
+    }),
+  ]),
+  loop_on_finish: z.boolean().optional(),
+  ignore_recycle_policy: z.boolean().optional(),
+  access_mode: accessModeSchema.optional(),
+  access_password: z.string().optional(),
+});
+
+export const channelFormSchema = z.object({
+  name: z.string().min(1, "Name is required"),
+  timezone: z.string().min(1, "Timezone is required"),
+  description: z.string().optional(),
+  blocks: z.array(blockSchema),
+  recycle_policy: z.object({
+    cooldown_days: z.number().int().min(0).nullable().optional(),
+    cooldown_generations: z.number().int().min(0).nullable().optional(),
+    min_available_ratio: z
+      .number()
+      .min(0, "Must be ≥ 0")
+      .max(1, "Must be ≤ 1"),
+  }),
+  auto_schedule: z.boolean(),
+  access_mode: accessModeSchema.optional(),
+  access_password: z.string().optional(),
+});
+
+export type FieldErrors = Record<string, string | undefined>;
+
+export function extractErrors(err: z.ZodError): FieldErrors {
+  const map: FieldErrors = {};
+  for (const issue of err.issues) {
+    const key = issue.path.join(".");
+    if (!map[key]) map[key] = issue.message;
+  }
+  return map;
+}