Fix #4312: a Shift move lands the selection's edges and centre on ruler guides

main lines a moved selection's edges and centre up with ruler guides
(snap_moved_to_rulers, #5746) but not when Shift keeps the move to its line. The
bounds now slide along that line onto a ruler guide the same way
(snap_moved_along_to_rulers), when nothing else lined up and the grabbed point is
not on a guide, within twice the Snap to Point distance along the line.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

docs/target-app-parity.md

@@ -2125,6 +2125,7 @@ Edit › Copy and Cut put the selected ruler guides on the clipboard, with the s
 | 2026-10-20 | minor | Type core: Hyphenation… and Justification… no longer listed as missing (done in #2310, #2755); evidence: a paragraph's Auto Leading drives the Character panel's Leading, the leading nudge and Fill with Placeholder Text; scores unchanged |
 | 2026-10-22 | minor | Drawing tools: a Pen, Anchor Point or Direct Selection drag's preview no longer stalls (#834: the position where the pointer re-entered the window could be skipped, and the move in the release's frame was lost); score and hours unchanged (estimated) |
 | 2026-10-23 | minor | Guides and snapping: a path moved by a press on its stroke or beside its edge (Selection, Group Selection, Direct Selection), and a straight segment Direct Selection drags, snap by the nearest point of the path, so the path lands exactly on a ruler guide with "align" instead of the pressed spot landing there and the path a few pixels beside it (#3701); `tests_prefs::a_move_held_by_a_paths_stroke_lands_the_path_on_a_ruler_guide`, `tests_prefs::a_straight_segment_dragged_by_direct_selection_lands_on_a_ruler_guide`. Score and hours unchanged. |
+| 2026-11-11 | minor | Guides and snapping: a Shift move slides the selection along its line onto a ruler guide by its edges and centre, as a move without Shift does (#4312); a guide a nearly parallel line only reaches a long way off pulls nothing. Score and hours unchanged (estimated). |
 | 2026-10-22 | minor | Live vector effects: the Transform effect has Transform Objects, Transform Patterns and Scale Strokes & Effects, its checkboxes visible (#885); the area row now lists only the options on a fill's or stroke's own Transform effect. Score and hours unchanged (estimated). |
 | 2026-10-23 | minor | COLR colour fonts (v0 and v1) draw and export as vector art; evidence added; scores unchanged. |
 | 2026-10-22 | minor | Libraries panel: the buttons beside the library picker show the items as icons (the default) or in a list, colours and graphics as rows with their names (a colour's hex value too), dragged and dropped by row; graphic thumbnails are shrunk to the size they are drawn at, so thin strokes stay whole. Tests: `panels::libraries::tests::the_list_view_shows_names_and_takes_drops_by_row`, `the_panel_draws_its_libraries`. Scores and hours unchanged. |