perf(scene): delta journal so edits touch only changed entities (phase 0-1)

Every geometry mutation previously bumped a monotonic geometry_epoch and each
derived cache compared its stamp and, on a miss, re-walked the whole document —
so drawing or moving one line rebuilt every hatch / image / mesh / wipeout model
even though none of them changed.

Add a per-mutation delta journal: bump_entities(&[(Handle, ChangeKind)]) records
exactly which handles changed (Added / Removed / Modified), folding the memo drop
and the epoch bump into one call a site cannot forget. A bounded ring keeps the
recent deltas; replay_since(last_epoch) coalesces the changes past a consumer or
returns None (full rebuild) when a spanned delta is `full` or the consumer fell
off the ring. bump_geometry / bump_geometry_no_blocks push a `full` delta so the
journal is never missing a step.

Route the common single-entity ops through it: add (Added), update (Modified),
erase (Removed), move/rotate/scale/mirror (Modified), copy (Added). Gate the four
per-category model caches on category relevance — an edit whose handles are not in
a category leaves that category cache warm; a removal is treated conservatively
(the erased handle can no longer be classified), and the mesh cache also
invalidates on any INSERT edit since it carries the instanced block meshes.

Net: a plain-entity edit no longer rebuilds the hatch/image/mesh/wipeout model
sets. The resident wire clone-all and the GPU re-upload are still whole-set — the
journal is the groundwork for making those per-entity next. Adds 6 journal unit
tests (replay, coalescing, full-fallback, ring overflow, category gate).

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

src/scene/selection.rs

@@ -329,6 +329,7 @@ impl Scene {
     // ── Erase ─────────────────────────────────────────────────────────────
 
     pub fn erase_entities(&mut self, handles: &[Handle]) {
+        let mut erased: Vec<(Handle, ChangeKind)> = Vec::new();
         for &h in handles {
             // Objects on a locked layer can't be erased.
             if self.is_layer_locked(h) {
@@ -339,7 +340,7 @@ impl Scene {
             self.hatches.remove(&h);
             self.meshes.remove(&h);
             self.solid_models.remove(&h);
-            self.mark_entity_dirty(h);
+            erased.push((h, ChangeKind::Removed));
         }
         // Remove erased handles from all groups; delete groups that become empty.
         let group_dict_handle = self.document.header.acad_group_dict_handle;
@@ -367,8 +368,10 @@ impl Scene {
             }
             self.document.objects.remove(gh);
         }
-        // Deleting top-level entities/inserts leaves block definitions intact;
-        // the erased handles were already dropped from the memo above.
-        self.bump_geometry_no_blocks();
+        // Deleting top-level entities/inserts leaves block definitions intact.
+        // Report the exact erased handles so derived caches drop just those and
+        // the resident set removes only their wires (bump_entities drops them
+        // from the tessellation memos too).
+        self.bump_entities(&erased);
     }
 }