v0.6.44 — Scene-fitted Kokoro narration (`reframe narrate` + `audio.narration`)

Added

Scene-fitted Kokoro narration (reframe narrate + audio.narration)

• New IR field AudioIR.narration — spoken voiceover lines ({ at, text, voice? })
  authored as a sibling <scene>-vo/script.json the scene imports. Each line resolves to a
  label-anchored file cue (so VO survives retiming/regen), with a baked duration
  sizing the bed's duck window. Additive + golden-safe (no narration → byte-identical plan).
• New command reframe narrate <scene> [--voice] [--max-speed] [--dry-run] — reads the
  compiled label clock, synthesizes each line with a Kokoro python sidecar (narrate.py),
  and auto-fits its speech rate to the slot between its anchor and the next line (bounded;
  warns if even max speed overruns). Bakes file/voice/speed/duration back into
  script.json (like assemble bakes ffprobe numbers). --dry-run prints the fit table from
  a length estimate with no synthesis.
• Kokoro is an optional dependency (pip install kokoro + espeak-ng), preflighted like
  ffmpeg/chromium. The .wav are external assets (same-machine, not golden) — the determinism
  contract still covers the AudioPlan, not the synthesized audio bytes.
• Example examples/scenes/narrated-demo.ts (+ narrated-demo-vo/script.json).