feat: adapt linescan scripts to use uv and proper rollover-based file saving

- Updated launch_with_signal.py with PEP 723 metadata for uv compatibility
- Added day/night mode presets with command-line arguments
- Implemented proper rollover-only file saving via Python/PIL callbacks
- Removed multifilesink from pipeline (was saving every frame incorrectly)
- Added funny auto-generated output directory names (e.g., fuzzy-photon)
- Updated rollover_example.py to follow same pattern with uv support
- Updated rollover_example.c to demonstrate signal detection without file saving
- Updated launch_with_capture.ps1 to remove incorrect multifilesink usage
- All scripts now save files ONLY on rollover events, not every frame
- Pipeline simplified: camera -> linescan -> display (files saved in callback)

gst/linescan/launch_with_capture.ps1

@@ -0,0 +1,43 @@
+# Linescan Pipeline Example - PowerShell GStreamer Launch
+#
+# This script demonstrates a GStreamer linescan pipeline using gst-launch-1.0.
+# NOTE: This saves EVERY frame using multifilesink, not just on rollover.
+#
+# For proper rollover-only saving, use the Python scripts instead:
+#   - launch_with_signal.py (full-featured with camera)
+#   - rollover_example.py (simple demo)
+#
+# This script is kept as a reference for the pipeline structure.
+#
+# Prerequisites:
+#   1. Build the plugins: .\build.ps1
+#   2. Run from workspace root: c:\dev\gst-plugins-vision
+#
+# Usage:
+#   .\gst\linescan\launch_with_capture.ps1
+#
+# Pipeline:
+#   idsueyesrc -> intervalometer -> videocrop -> queue -> linescan -> videoconvert -> autovideosink
+#
+# WARNING: This example saves every output frame, not just on rollover!
+# Use Python scripts for rollover-based capture.
+
+$env:GST_DEBUG="linescan:5"
+
+# Simple pipeline - display only (no file saving)
+# For file saving on rollover, use launch_with_signal.py instead
+gst-launch-1.0 idsueyesrc config-file=ini/roi-night.ini `
+    exposure=5.25 framerate=200 gain=42 name=cam device-id=2 ! `
+    intervalometer enabled=true camera-element=cam `
+    ramp-rate=vslow `
+    update-interval=1000 `
+    gain-max=52 `
+    log-file=linescan_timelapse.csv ! `
+    videocrop bottom=3 ! `
+    queue ! `
+    linescan direction=vertical output-size=1900 ! `
+    videoconvert ! autovideosink
+
+# Note: multifilesink has been removed because it saves EVERY frame.
+# To save only on rollover events, use the Python scripts which connect
+# to the rollover signal and save via PIL/numpy.