docs: one line per behaviour change in the rc.166 changelog, named by program

The section had grown to eighteen entries, several of them describing the same report or carrying
detail that belongs in a commit message. Consolidated to thirteen one-liners, each naming the program
it concerns - rugnux, jfjoch_writer, jfjoch_broker, jfjoch_viewer - so a reader can find what changed
in the part they use.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EFEJG6WBQv8th4UJFNe53N

docs/CHANGELOG.md

@@ -3,24 +3,19 @@
 
 ### 1.0.0-rc.166
 
-* `rugnux --mode calibration` writes `<prefix>.json` beside the `.poni`, whose `dataset_settings` member is a `jfjoch_broker` `dataset_settings` body as it stands.
-* `rugnux` and `jfjoch_viewer` read PILATUS miniCBF sweeps natively, without conversion.
-* Masters written by other facilities open, including Eiger 1.x and third-party NXmx variants.
+* `rugnux` reads PILATUS miniCBF sweeps natively, and opens masters written at other facilities, including Eiger 1.x and third-party NXmx.
 * `rugnux` measures the beam centre on every run, and indexes with it when the file's value indexes nothing.
-* A detector swung out on a 2theta arm is placed where the file says it stands, and the calibration can hold the tilt fixed.
-* `rugnux` writes the unmerged MTZ by default, and a P1 merge beside it, so a wrong space group can be re-merged without reprocessing.
-* Significant improvements to symmetry handling in `rugnux`: the lattice, the point group, the setting and the systematic absences.
-* The `rugnux` report gives the resolution the CC1/2 fit reached, beside the range the reflections were written to.
-* The `rugnux` report gives the twinning statistics measured before the space group was decided, beside the ones measured after.
-* The `rugnux` report gives the strong-direction diffraction limit, and warns when CC1/2 is not monotone with resolution.
-* `rugnux` ranks screw axes on the evidence their absences carry, rather than on how many control reflections a candidate happens to have.
-* The `rugnux` two-pass decision no longer reports a completeness it did not measure.
-* Twinning is no longer reported when the L-test contradicts it.
-* The `rugnux` report gives the detector tilt, the measured tilt and the direct beam beside the beam centre, and a post-refined beam centre is judged against the run's own measurement rather than the file's.
-* `--no-refine-tilt` holds the detector tilt at the value in the file, instead of zeroing it, when the calibration starts from the spots.
-* The HDF5 master file and the CBOR start message carry `direct_beam_x`/`direct_beam_y`, where the undeflected beam lands on the detector, beside the `beam_center_x`/`beam_center_y` PONI.
-* The `rugnux` report says what its measured detector tilt is worth: one sweep determines the direct beam rather than the tilt itself, and only the median over several crystals on one detector is comparable with a powder calibration.
-* The `jfjoch_viewer` grid scan view draws the cells in the proportion of the scan steps, so the map has the shape of the scanned area.
+* `rugnux` places a detector swung out on a 2theta arm where the file says it stands.
+* `rugnux` writes the unmerged MTZ by default, with a P1 merge beside it, so a wrong space group can be re-merged without reprocessing.
+* `rugnux` handles symmetry better: the lattice, the point group, the setting and the systematic absences.
+* `rugnux` reports the detector geometry it measured - the direct beam, the tilt and the beam centre - and what a single sweep can and cannot determine.
+* `rugnux` reports the resolution the CC1/2 fit reached and the strong-direction diffraction limit.
+* `rugnux` reports twinning measured before and after the space group was decided, and no longer reports it when the L-test contradicts it.
+* `rugnux --mode calibration` writes `<prefix>.json` beside the `.poni`, holding the geometry as a `jfjoch_broker` `dataset_settings` body.
+* `rugnux --no-refine-tilt` holds the detector tilt at the value in the file instead of zeroing it.
+* `jfjoch_writer` writes `direct_beam_x`/`direct_beam_y` in the HDF5 master - where the undeflected beam lands - beside the `beam_center_x`/`beam_center_y` PONI.
+* `jfjoch_broker` sends `direct_beam_x`/`direct_beam_y` on the CBOR start message.
+* `jfjoch_viewer` reads PILATUS miniCBF sweeps natively, and draws grid scan cells in the proportion of the scan steps.
 
 ### 1.0.0-rc.165
 This is an UNSTABLE release. It includes many experimental features, as well as many AI generated fixes. We recommend using rc.152 for production use.