fix(player): clamp seeks inside media to stop end-of-stream pause loop (DR-095)

Seeking near the end of a transcoded video locked the player into a
stall/pause loop: unpausing or skipping bounced straight back to paused.

Both seek paths clamped the target to exactly `duration`. hls.js then
requested the segment whose start time lies *past* the end of the media
(a 6330.324s item asks for segment 1055, starting at 6336.33s). Jellyfin
never produces that segment, the fetch times out, and the gap-controller
stalls forever at the last buffered position — retrying ~1x/second and
firing an endless stream of AbortErrors as play() lands mid-nudge.

Clamp strictly inside the media instead, keeping one segment length
(6s) of margin, floored at 0 so short media still seeks to the start.
The seek-bar drag path needed this too: its range input `max` is the
duration itself, so dragging fully right produced the same dead target.

Also bumps the requirement-count fixture for the new DR-095 row.

src/lib/components/player/tapGestures.test.ts

@@ -6,6 +6,8 @@ import {
   createTapGestureState,
   registerTap,
   resolveSeekTarget,
+  clampSeekTarget,
+  END_SEEK_MARGIN_SECONDS,
 } from "./tapGestures";
 
 const SCREEN_WIDTH = 1000;
@@ -123,8 +125,28 @@ describe("seek target resolution", () => {
     expect(resolveSeekTarget({ delta: -10, reportedPosition: 4, duration: DURATION })).toBe(0);
   });
 
-  it("clamps to the duration when skipping past the end", () => {
-    expect(resolveSeekTarget({ delta: 30, reportedPosition: 590, duration: DURATION })).toBe(DURATION);
+  it("clamps short of the duration when skipping past the end", () => {
+    // Never land exactly on `duration`: hls.js would then request the segment
+    // that starts at/after the media end, which the server never produces —
+    // the fetch times out and the gap-controller stalls in a pause loop.
+    expect(resolveSeekTarget({ delta: 30, reportedPosition: 590, duration: DURATION })).toBe(
+      DURATION - END_SEEK_MARGIN_SECONDS
+    );
+  });
+
+  it("keeps the end clamp strictly inside the media for a long transcoded item", () => {
+    // Regression: seeking near the end of a ~105min transcoded item clamped to
+    // the exact runtime (6330.324s), making hls.js fetch segment 1055 which
+    // starts at 6336.33s — past the end. That segment 404s/times out forever.
+    const runtime = 6330.324;
+    const target = resolveSeekTarget({ delta: 30, reportedPosition: 6320, duration: runtime });
+
+    expect(target).toBeLessThan(runtime);
+    expect(target).toBeCloseTo(runtime - END_SEEK_MARGIN_SECONDS, 5);
+  });
+
+  it("does not clamp below zero for media shorter than the end margin", () => {
+    expect(resolveSeekTarget({ delta: 30, reportedPosition: 1, duration: 1 })).toBe(0);
   });
 
   it("chains off a pending target so rapid taps do not compound off a stale position", () => {
@@ -156,3 +178,24 @@ describe("seek target resolution", () => {
     expect(resolveSeekTarget({ delta: 30, reportedPosition: 100, duration: 0 })).toBe(130);
   });
 });
+
+describe("seek target clamping (shared by skip and seek-bar drag)", () => {
+  it("keeps a mid-stream target untouched", () => {
+    expect(clampSeekTarget(100, 600)).toBe(100);
+  });
+
+  it("pulls a drag to the very end back inside the media", () => {
+    // The seek bar's max IS the duration, so dragging fully right yields
+    // exactly `duration` — the value that triggers the dead-segment stall.
+    expect(clampSeekTarget(6330.324, 6330.324)).toBeCloseTo(6330.324 - END_SEEK_MARGIN_SECONDS, 5);
+  });
+
+  it("clamps negative and non-finite targets to zero", () => {
+    expect(clampSeekTarget(-5, 600)).toBe(0);
+    expect(clampSeekTarget(NaN, 600)).toBe(0);
+  });
+
+  it("leaves the target alone when the duration is unknown", () => {
+    expect(clampSeekTarget(500, 0)).toBe(500);
+  });
+});