feat: add Svelte stores for app state

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/src/lib/stores.ts

@@ -0,0 +1,66 @@
+import { writable, derived } from "svelte/store";
+import type { VideoFile, Marker } from "./api";
+
+// --- Connection ---
+export const serverUrl = writable("http://192.168.1.51:8000");
+
+// --- Files ---
+export const roots = writable<string[]>([]);
+export const files = writable<VideoFile[]>([]);
+export const hiddenFiles = writable<Set<string>>(new Set());
+export const currentFile = writable<VideoFile | null>(null);
+export const hideExported = writable(false);
+export const showHidden = writable(false);
+
+// --- Playback ---
+export const duration = writable(0);
+export const cursor = writable(0);
+export const playPos = writable<number | null>(null);
+export const playing = writable(false);
+export const quality = writable("low");
+
+// --- Timeline ---
+export const markers = writable<Marker[]>([]);
+export const locked = writable(false);
+
+// --- Export settings ---
+export const clips = writable(3);
+export const spread = writable(3.0);
+export const shortSide = writable<number | null>(512);
+export const portraitRatio = writable<string | null>(null);
+export const cropCenter = writable(0.5);
+export const format = writable("MP4");
+export const hwEncode = writable(false);
+export const label = writable("");
+export const category = writable("");
+export const clipName = writable("");
+export const exportFolder = writable("");
+export const encoder = writable("libx264");
+export const trackSubject = writable(false);
+export const randPortrait = writable(false);
+export const randSquare = writable(false);
+
+// --- Profiles ---
+export const profile = writable("default");
+export const subprofiles = writable<string[]>([]);
+
+// --- Export progress ---
+export const exportStatus = writable<string>("idle"); // idle | running | done | error
+export const exportCompleted = writable(0);
+export const exportTotal = writable(0);
+
+// --- Derived ---
+export const clipSpan = derived(
+  [clips, spread],
+  ([$clips, $spread]) => 8.0 + ($clips - 1) * $spread
+);
+
+export const visibleFiles = derived(
+  [files, hiddenFiles, showHidden],
+  ([$files, $hidden, $showHidden]) => {
+    return $files.filter(f => {
+      if (!$showHidden && $hidden.has(f.name)) return false;
+      return true;
+    });
+  }
+);