refactor(highway): lift 79 per-instance closure vars into hwState (R3c H lift) (#849)

* refactor(highway): lift 79 per-instance closure vars into `hwState` (R3c H lift)

Collapses createHighway()'s 79 mutable closure `let`s into one per-instance
`hwState` object. Scope-resolved rewrite via acorn + eslint-scope: 1059 edits
(1057 references + 79 defs - the deleted `let canvas, ctx, ws`), with the four
names shadowed in inner scopes (chartTime/ctx/notes/chordTemplates) resolved
correctly so only closure-bound refs move. Enables the later module split:
extracted renderer/ws modules close over `hwState` as a factory arg, so
multi-panel plugins (highway_3d, note_detect, splitscreen) don't share one
highway's state.

Container is `hwState`, NOT `H` — `H` is already canvas height (70 uses). The
frame-time gate caught that collision instantly (0 draws, `H._drawHooks is not
iterable` in the shared draw-hook path).

PERF (the whole risk): identical to the pre-lift baseline. Draw p50 2.1-2.2 ms,
p95 2.7-3.0 ms (pre-lift 2.7-3.2), measured on the Arcturus feedpak, headless.
Each closure-slot read became a `hwState.<slot>` monomorphic property load; the
hot loop pays nothing. On-device: Byron confirmed the 2D highway plays smoothly.

Tests: the ~30 highway JS suites brace-extract functions/patterns from the
source; their state references + the monotonic-clock vm sandbox now use
`hwState.<slot>` (the const _CHART_MAX_INTERP_MS etc. stay top-level, not
lifted). node --test: 1030/1030 green. Two self-inflicted over-replacements
caught and reverted (`_lefty` is a prefix of the 3D-local `_leftyCached`;
`STRING_COLORS` a suffix of `DEFAULT_STRING_COLORS`) — substring replaces on the
brace-extract regexes need word care.

Transformer saved at ~/.local/share/feedback-editor/highway-h-lift.mjs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* test(highway): pin the setNoteStateProvider assertion to hwState._noteStateProvider (CodeRabbit)

The [^}]* form matched an unqualified _noteStateProvider =, so a regression to
closure-level state could still pass. Require the hwState-qualified assignment.

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/js/highway_note_state.test.js

@@ -34,16 +34,16 @@ function extractBlock(src, signature) {
 
 test('highway declares the note-state provider slot', () => {
     const src = fs.readFileSync(highwayJs, 'utf8');
-    assert.match(src, /let\s+_noteStateProvider\s*=\s*null/, 'missing _noteStateProvider (provider slot, null = none)');
+    assert.match(src, /hwState\._noteStateProvider\s*=\s*null/, 'missing _noteStateProvider (provider slot, null = none)');
 });
 
 test('public API exposes setNoteStateProvider / getNoteStateProvider / getNoteState / isDefaultRenderer', () => {
     const src = fs.readFileSync(highwayJs, 'utf8');
-    assert.match(src, /setNoteStateProvider\s*\(\s*fn\s*\)\s*\{[^}]*_noteStateProvider\s*=/, 'setNoteStateProvider must assign _noteStateProvider');
+    assert.match(src, /setNoteStateProvider\s*\(\s*fn\s*\)\s*\{[^}]*hwState\._noteStateProvider\s*=/, 'setNoteStateProvider must assign _noteStateProvider');
     assert.match(src, /setNoteStateProvider\s*\(\s*fn\s*\)\s*\{[^}]*typeof\s+fn\s*===\s*['"]function['"][^}]*:\s*null/, 'setNoteStateProvider must coerce non-functions (incl. null) to null');
-    assert.match(src, /getNoteStateProvider\s*\(\s*\)\s*\{\s*return\s+_noteStateProvider/, 'getNoteStateProvider must return the slot');
+    assert.match(src, /getNoteStateProvider\s*\(\s*\)\s*\{\s*return\s+hwState\._noteStateProvider/, 'getNoteStateProvider must return the slot');
     assert.match(src, /getNoteState\s*\(\s*note\s*,\s*chartTime\s*\)\s*\{\s*return\s+_noteState\s*\(/, 'getNoteState must delegate to _noteState');
-    assert.match(src, /isDefaultRenderer\s*\(\s*\)\s*\{\s*return\s+_renderer\s*===\s*_defaultRenderer\s*\|\|\s*_renderer\s*==\s*null/, 'isDefaultRenderer must be (_renderer === _defaultRenderer || _renderer == null)');
+    assert.match(src, /isDefaultRenderer\s*\(\s*\)\s*\{\s*return\s+hwState\._renderer\s*===\s*_defaultRenderer\s*\|\|\s*hwState\._renderer\s*==\s*null/, 'isDefaultRenderer must be (_renderer === _defaultRenderer || _renderer == null)');
 });
 
 test('_makeBundle exposes getNoteState (stable reference, no per-frame alloc)', () => {
@@ -72,7 +72,7 @@ test('_makeBundle exposes getNoteStateProvider as a stable reference (feedBack#2
     // slot, so renderers see a live "is a provider registered?" view.
     assert.match(
         src,
-        /function\s+_getNoteStateProvider\s*\(\s*\)\s*\{\s*return\s+_noteStateProvider\s*;?\s*\}/,
+        /function\s+_getNoteStateProvider\s*\(\s*\)\s*\{\s*return\s+hwState\._noteStateProvider\s*;?\s*\}/,
         '_getNoteStateProvider must be defined as a stable named function returning _noteStateProvider'
     );
 });
@@ -80,7 +80,7 @@ test('_makeBundle exposes getNoteStateProvider as a stable reference (feedBack#2
 test('_noteState normalizes provider output as documented', () => {
     const src = fs.readFileSync(highwayJs, 'utf8');
     const fn = extractBlock(src, 'function _noteState(note, chartTime)');
-    assert.match(fn, /if\s*\(\s*!_noteStateProvider\s*\)\s*return\s+null/, 'must short-circuit when no provider is registered');
+    assert.match(fn, /if\s*\(\s*!hwState\._noteStateProvider\s*\)\s*return\s+null/, 'must short-circuit when no provider is registered');
     assert.match(fn, /try\s*\{[\s\S]*_noteStateProvider\s*\([\s\S]*catch[\s\S]*return\s+null/, 'must call the provider inside try/catch and return null on throw');
     assert.match(fn, /state\s*!==\s*['"]hit['"]\s*&&\s*state\s*!==\s*['"]active['"]\s*&&\s*state\s*!==\s*['"]miss['"]/, 'must reject states other than hit/active/miss');
     assert.match(fn, /Math\.max\(\s*0\s*,\s*Math\.min\(\s*1\s*,\s*raw\.alpha\s*\)\s*\)/, 'must clamp alpha to [0,1]');