v5: refactor into modular stream_tools desktop app

Same inaSpeechSegmenter engine split into reusable core/ (fftools, segmenter, exporters) + utils/ and a CustomTkinter multi-tab UI. Adds JSON and ffmpeg-script export. Extracted from the stream_tools app.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

utils/formats.py

@@ -0,0 +1,42 @@
+"""
+Timecode & duration formatting utilities.
+"""
+
+
+def fmt_dur(seconds: float) -> str:
+    """Format a duration as H:MM:SS or M:SS for display."""
+    if seconds < 0:
+        return "…"
+    if seconds == 0:
+        return "—"
+    s = int(round(seconds))
+    h, rem = divmod(s, 3600)
+    m, sec = divmod(rem, 60)
+    return f"{h}:{m:02d}:{sec:02d}" if h else f"{m}:{sec:02d}"
+
+
+def fmt_elapsed(s: float) -> str:
+    if s < 60:
+        return f"{int(s)}s"
+    m, sec = divmod(int(s), 60)
+    return f"{m}m {sec:02d}s"
+
+
+def format_timecode(seconds: float) -> str:
+    """Format seconds as HH:MM:SS."""
+    h = int(seconds // 3600)
+    m = int((seconds % 3600) // 60)
+    s = int(seconds % 60)
+    return f"{h:02d}:{m:02d}:{s:02d}"
+
+
+def seconds_to_smpte(seconds: float, fps: float = 29.97) -> str:
+    """Convert seconds to SMPTE timecode HH:MM:SS:FF."""
+    total_frames = int(seconds * fps)
+    ff = total_frames % int(round(fps))
+    total_seconds = total_frames // int(round(fps))
+    ss = total_seconds % 60
+    total_minutes = total_seconds // 60
+    mm = total_minutes % 60
+    hh = total_minutes // 60
+    return f"{hh:02d}:{mm:02d}:{ss:02d}:{ff:02d}"