Merge branch 'main' into feature/parametric-constraint-system

Brings in 54 commits from origin/main: a selection-performance overhaul,
surface thickening, GPU-native wide/tapered stroke rendering, continued
ocs_doc_api evolution, and assorted fixes/polish (block double-click
editing, DWG hatch/database repair, clipboard, collapsible Properties
sections).

Six real conflicts, all where this branch had independently re-applied
a fix upstream later revised or already carried natively:

- src/app/automation.rs, src/app/command_driver.rs: combined both
  sides — kept this branch's sketch-constraint/named-parameter loading
  on "new"/"open", adopted main's Scene::clear()/material_base_dir and
  its newer rebuild_derived_caches() over the older bump_geometry().
  Scene::clear() (src/scene/entity.rs) now also resets
  sketch_constraints/named_parameters, so every caller gets this for
  free instead of each call site repeating it.
- src/io/mod.rs, src/scene/render_graph.rs: adopted main's design
  outright (commit 973af87d, authored by Hakan directly) — a large
  MINSERT is no longer purged as "corrupt" at load, only its rendering
  is bounded, preserving the source data. This branch's own earlier
  design (reject at load) predates that revision.
- src/scene/pipeline/mesh_gpu.rs: adopted main's valid_rgba_size()
  guard (a real robustness improvement over this branch's version).
- src/snap.rs: replaced wholesale with main's version — this branch's
  copy was an explicit verbatim snapshot from an earlier upstream PR
  (commit 4c264b8c) with zero constraint-system-specific content, and
  main has since evolved it considerably further.

Also removed two now-dead duplicates the merge surfaced without a
conflict marker (both branches had independently fixed the same
things): the OPTIONS/OP command dispatch/autocomplete entries, and
automation.rs's open_finalizes_and_purges_like_the_ui_open_path test
(kept main's version, which covers strictly more: solid_models/
material_base_dir reset on "new").

Full workspace suite passes (812 lib tests + this branch's own 24
constraint/persistence integration tests) except the one pre-existing,
unrelated font-test failure already present on main. Zero clippy
findings in the hand-written merge resolution itself; the ~1,171
warnings clippy reports are pre-existing in the 54 absorbed commits,
not introduced here.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/update/file.rs

@@ -365,6 +365,9 @@ impl OpenCADStudio {
             zoom_factor: self.zoom_factor,
             cursor_size: self.cursor_size,
             pick_box: self.pick_box,
+            double_click_block_refedit: self.double_click_block_refedit,
+            double_click_block_attedit: self.double_click_block_attedit,
+            grip_object_limit: self.grip_object_limit,
             cursor_type: self.cursor_type,
             crosshair_color: self.crosshair_color,
             lineweight_display_scale: self.lineweight_display_scale,
@@ -420,6 +423,9 @@ impl OpenCADStudio {
         self.zoom_factor = s.zoom_factor.clamp(3, 100);
         self.cursor_size = s.cursor_size.clamp(1, 100);
         self.pick_box = s.pick_box.clamp(0, 50);
+        self.double_click_block_refedit = s.double_click_block_refedit;
+        self.double_click_block_attedit = s.double_click_block_attedit;
+        self.grip_object_limit = s.grip_object_limit.clamp(0, 32767);
         self.cursor_type = s.cursor_type;
         self.crosshair_color = s.crosshair_color;
         self.crosshair_color_input = s