fix(dimension): bake↔live consistency, edits, baseline/continue, grips

Batch 1-3 of the dimension audit (19 issues). The dominant class was the
baked *D block diverging from the live render: a reloaded dimension renders
from that block, so on save+reopen it silently changed.

Bake now matches the live render:
- text value/format via the shared style-resolved path (DIMDEC/DIMLFAC/
  DIMPOST/units/<>), correct height + rotation ladder, suppression
- angular dims bake their swept arc (no longer collapse to a V)
- diameter draws edge-to-edge through the centre (live + bake), centre mark
- radius/linear/aligned bake arrowheads
- group-10 (base.definition_point) synced from the edited geometry so an
  edited dim no longer shifts on reload

Editing / properties:
- aligned no longer corrupts ext_line_rotation when a coordinate is edited
- DIMTEDIT pins the moved text (text_user_positioned)
- angle properties shown/edited in degrees
- non-linear text respects the user-positioned gate

Commands / geometry:
- DIMBASELINE stacks outward (not toward the points) and its preview no
  longer tilts over non-level points
- DIMCONTINUE/DIMBASELINE inherit the base dim's text rotation (UCS chains)
- angular extension lines reach the arc (no gap)
- text grip sits on the text for auto-placed dims instead of the origin

Refs #181. (acadrust DXF round-trip + QDIM/DIMBREAK/DIMJOGLINE/DIMSPACE/
DIMEDIT to follow.)

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

src/modules/annotate/dimtedit.rs

@@ -78,6 +78,9 @@ impl CadCommand for DimTeditCommand {
                         acadrust::types::Vector3::new(pt.x as f64, pt.y as f64, pt.z as f64);
                     d.base_mut().text_middle_point = new_pt;
                     d.base_mut().insertion_point = new_pt;
+                    // Pin the text to this location, else the renderer recomputes
+                    // the style-default placement and the move is discarded.
+                    d.base_mut().text_user_positioned = true;
                 }
                 return CmdResult::ReplaceEntity(h, vec![ent]);
             }