feat: tag chips count their channels, Plex shows a file's size, a skip waits, Continue watching opens whole

The channel manager's tag chips carry a muted count. A Plex item's Info page names the file's size.
An auto-skip's countdown starts 3 s into the marker, with its button there from the start and a delay of
0 still immediate. Continue watching has a See all, opening Browse on in progress, last watched first;
Recently added's sets the watch state back so it opens what it says.

frontend/src/lib/api/plex.ts

@@ -154,6 +154,7 @@ export interface PlexItemDetail {
   summary?: string | null;
   year?: number | null;
   duration_seconds: number | null;
+  size_bytes?: number | null; // the file's, null while unknown
   playable: string; // direct | remux | transcode
   transcode_hw?: boolean | null; // transcode items only: true = HW-capable, false = SW-only, null = n/a
   codec_video?: string | null; // e.g. "hevc" / "h264" (info-chip subtitle)

frontend/src/lib/plexPlayerHooks.ts

@@ -434,6 +434,9 @@ export function usePlayerVolume(opts: {
   return { setVol, nudgeVolume, toggleMute, onWheel };
 }
 
+// How long a marker plays before an auto-skip's countdown starts (seconds).
+const AUTO_SKIP_WAIT_S = 3;
+
 // Auto-skip intro/credits. Entering a marker whose auto-skip is on runs a countdown (skipProgress
 // 0→1 over autoSkipDelay s, shown on the Skip button); on completion it skips — to the marker end, or
 // for the credits that end the item to the next item (binge). Which credits those are, and which the
@@ -538,14 +541,16 @@ export function useAutoSkip(opts: {
     const enabled = (m.type === "intro" ? autoSkipIntro : autoSkipCredits) && activeAuto;
     if (!enabled || suspended || cancelledMarkerRef.current === key) return setSkipProgress(null);
     if (autoSkipDelay <= 0) return doSkip(m); // immediate
-    let elapsed = 0;
+    // Below zero is the wait: time to see where the marker has landed and press the button, which
+    // shows from the start, before anything counts down to leaving. A delay of 0 asked for none.
+    let elapsed = -AUTO_SKIP_WAIT_S;
     setSkipProgress(0);
     const iv = window.setInterval(() => {
       // Freeze the countdown while the video is paused — otherwise it would fire and auto-seek a
       // deliberately-paused video. It resumes from where it stopped when playback resumes.
       if (videoRef.current?.paused) return;
       elapsed += 0.1;
-      const p = Math.min(1, elapsed / autoSkipDelay);
+      const p = Math.max(0, Math.min(1, elapsed / autoSkipDelay));
       setSkipProgress(p);
       if (p >= 1) {
         window.clearInterval(iv);