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/handshapes_pipeline.test.js

@@ -33,7 +33,7 @@ test('handshapes WS case accumulates incoming chunks into handShapes', () => {
     const block = getCaseBlock(src, 'handshapes');
     assert.match(
         block,
-        /handShapes\s*=\s*handShapes\.concat\(\s*msg\.data\s*\)/,
+        /hwState\.handShapes\s*=\s*hwState\.handShapes\.concat\(\s*msg\.data\s*\)/,
         'handshapes case must concat msg.data into the handShapes accumulator',
     );
 });
@@ -62,7 +62,7 @@ test('bundle exposes handShapes to renderers with flat-list fallback', () => {
     const src = fs.readFileSync(HIGHWAY_JS, 'utf8');
     assert.match(
         src,
-        /\bhandShapes\s*[:=]\s*\([^)]*_filteredHandShapes[^)]*\)\s*\?\s*_filteredHandShapes\s*:\s*handShapes\b/,
+        /\bhandShapes\s*[:=]\s*\([^)]*hwState\._filteredHandShapes[^)]*\)\s*\?\s*hwState\._filteredHandShapes\s*:\s*hwState\.handShapes\b/,
         'bundle must expose handShapes with the _filteredHandShapes-vs-handShapes ternary fallback',
     );
 });