Fix cutter-report clip duration: render full beat / match length

Bug: the report rendered every preview clip at most 3 s, so any beat longer
than 3 s (e.g. beat 02 at 8.56 s) only got a fragment in the cutter report
and looked wrong. The hard 3 s cap was an early prototype constant that
silently truncated normal-length beats.

Trailer clip is now the full beat duration so the cutter sees the entire
reference beat. Source clip is the full matched duration (may be shorter
than the beat when the match drops before the beat ends — that's correct,
the cutter needs to see exactly the matched span).

A 30 s safety cap stays as a guard against runaway durations but it should
never trip on a normal trailer beat.

All existing clips were dropped and re-rendered so the report on disk
matches the new logic.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/generate_cutter_report.py

@@ -129,7 +129,11 @@ def parse_field(desc: str | None, key: str) -> str:
 STILL_WIDTH = 480
 STILL_QUALITY = 4
 CLIP_WIDTH = 480
-CLIP_DURATION_S = 3.0
+# Clips run for the full beat / match duration, with this cap as a safety net
+# so a runaway match doesn't pull a 60 s preview. Most beats are below 10 s
+# anyway. The cap should never silently truncate a normal beat — set it well
+# above any realistic beat length.
+CLIP_MAX_DURATION_S = 30.0
 
 
 def _stale(out: Path, src: Path) -> bool:
@@ -265,13 +269,18 @@ def collect_rows(
                 if extract_still(source_path, s_still, sjpg):
                     source_still = sjpg
         if with_clips:
-            tdur = min(CLIP_DURATION_S, max(0.5, beat["end_s"] - beat["start_s"]))
+            # Trailer clip: full beat duration so the cutter sees the entire
+            # reference beat, not an arbitrary-length excerpt.
+            tdur = max(0.5, min(CLIP_MAX_DURATION_S, beat["end_s"] - beat["start_s"]))
             tmp4 = clips_dir / f"beat_{bid:02d}_trailer.mp4"
             if extract_clip(trailer_path, beat["start_s"], tdur, tmp4):
                 trailer_clip = tmp4
+            # Source clip: full matched duration. May be shorter than the beat
+            # when the match drops out before the beat ends (fade / shot
+            # change in the source); that's intentional — the cutter needs to
+            # see exactly the matched span.
             if rec is not None:
-                src_dur = max(0.5, rec["out_point_s"] - rec["in_point_s"])
+                sdur = max(0.5, min(CLIP_MAX_DURATION_S, rec["out_point_s"] - rec["in_point_s"]))
-                sdur = min(CLIP_DURATION_S, src_dur)
                 smp4 = clips_dir / f"beat_{bid:02d}_source.mp4"
                 if extract_clip(source_path, rec["in_point_s"], sdur, smp4):
                     source_clip = smp4