Restructure as a self-contained Agent Skills package (fix Codex install)

Move the skill into skills/watch/ so SKILL.md and its scripts/ runtime are
siblings inside one folder. `npx skills add` (Codex/Cursor/Copilot/agents) now
copies a working skill as a unit; previously it grabbed the root SKILL.md alone
and left scripts/ behind, so the skill was dead on arrival on every non-Claude
host. Mirrors the layout last30days-skill adopted for the same reason.

- skills/watch/{SKILL.md,scripts/}: self-contained skill folder
- SKILL.md: resolve a harness-agnostic $SKILL_DIR (the dir it was Read from)
  instead of the Claude-Code-only ${CLAUDE_SKILL_DIR}; guard + 19 call sites
- drop commands/watch.md: /watch derives from frontmatter (name + user-invocable)
- .codex-plugin/plugin.json: full manifest with "skills": "./skills/" + interface
- add .agents/plugins/marketplace.json, AGENTS.md, CLAUDE.md, .skillignore
- build-skill.sh: archive the skills/watch subtree (one SKILL.md, no zip -d)
- fix paths in tests, hooks hint, .gitattributes, release.yml
- relocate dev-sync.sh to repo root and fix REPO_ROOT
- README: content-ideas structure, npx skills install, star history

Verified: 37/37 tests pass; npx skills add bundles the full scripts/ runtime;
manifests valid; versions synced at 0.1.3.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_timestamps.py

@@ -0,0 +1,87 @@
+"""Transcript-cue timestamps: parsing, point extraction, and pinned merge."""
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+
+import frames
+
+
+def test_parse_timestamps_mixed_formats():
+    assert frames.parse_timestamps("30,1:05,90") == [30.0, 65.0, 90.0]
+
+
+def test_parse_timestamps_strips_and_dedupes():
+    assert frames.parse_timestamps(" 90 , 30, 30 ") == [30.0, 90.0]
+
+
+def test_parse_timestamps_empty():
+    assert frames.parse_timestamps("") == []
+    assert frames.parse_timestamps("  ,  ") == []
+
+
+def test_parse_timestamps_rejects_garbage():
+    with pytest.raises(SystemExit):
+        frames.parse_timestamps("4:bad")
+
+
+def test_merge_frames_sorts_and_reindexes():
+    primary = [
+        {"index": 0, "timestamp_seconds": 1.0, "path": "a", "reason": "scene-change"},
+        {"index": 1, "timestamp_seconds": 5.0, "path": "b", "reason": "scene-change"},
+    ]
+    pinned = [
+        {"index": 0, "timestamp_seconds": 3.0, "path": "c", "reason": "transcript-cue"},
+    ]
+    merged = frames.merge_frames(primary, pinned)
+    assert [f["path"] for f in merged] == ["a", "c", "b"]
+    assert [f["index"] for f in merged] == [0, 1, 2]
+    assert merged[1]["reason"] == "transcript-cue"
+
+
+def test_merge_frames_keeps_all_pinned():
+    pinned = [{"index": 0, "timestamp_seconds": 2.0, "path": "c", "reason": "transcript-cue"}]
+    merged = frames.merge_frames([], pinned)
+    assert [f["path"] for f in merged] == ["c"]
+
+
+def test_extract_at_timestamps_one_frame_per_point(cut_clip: Path, tmp_path: Path):
+    out, meta = frames.extract_at_timestamps(str(cut_clip), tmp_path / "f", [0.5, 2.0, 4.0])
+    assert meta["engine"] == "timestamps"
+    assert meta["fallback"] is False
+    assert len(out) == 3
+    assert all(f["reason"] == "transcript-cue" for f in out)
+    ts = [f["timestamp_seconds"] for f in out]
+    assert ts == sorted(ts)
+    assert len(out) == len(list((tmp_path / "f").glob("cue_*.jpg")))
+
+
+def test_extract_at_timestamps_drops_out_of_window(cut_clip: Path, tmp_path: Path):
+    out, meta = frames.extract_at_timestamps(
+        str(cut_clip), tmp_path / "f", [0.5, 2.0, 4.0],
+        start_seconds=1.0, end_seconds=3.0,
+    )
+    assert [f["timestamp_seconds"] for f in out] == [2.0]
+    assert meta["dropped_out_of_window"] == 2
+
+
+def test_extract_at_timestamps_caps_and_spans(cut_clip: Path, tmp_path: Path):
+    out, meta = frames.extract_at_timestamps(
+        str(cut_clip), tmp_path / "f", [0.5, 1.5, 2.5, 3.5, 4.5], max_frames=3,
+    )
+    assert len(out) == 3
+    ts = [f["timestamp_seconds"] for f in out]
+    assert ts[0] == 0.5 and ts[-1] == 4.5  # even-sample keeps first + last
+    assert len(out) == len(list((tmp_path / "f").glob("cue_*.jpg")))
+
+
+def test_extract_at_timestamps_does_not_clobber_detail_frames(cut_clip: Path, tmp_path: Path):
+    """Cue frames live alongside detail frames in the same dir without deleting them."""
+    d = tmp_path / "f"
+    scene, _ = frames.extract_scene_or_uniform(
+        str(cut_clip), d, fps=2.0, target_frames=50, max_frames=100,
+    )
+    cues, _ = frames.extract_at_timestamps(str(cut_clip), d, [1.0, 3.0])
+    assert len(list(d.glob("frame_*.jpg"))) == len(scene)
+    assert len(list(d.glob("cue_*.jpg"))) == len(cues)