feat(h3d-carve-15): extract U-section (per-frame renderer) into src/renderer.js

- createRenderer factory DI: 241 params (consts, fn-refs, 33 pool getters,
  material/settings/camera/ND getters, 35 setters)
- screen.js: tombstone + createRenderer wiring after createNoteRenderer +
  createCamera wirings (§1 ruling: createNoteRenderer called from screen.js)
- Restore createArp wiring + _resetStringDependentCaches to screen.js
  (accidentally dropped during carve; both needed in IIFE scope)
- smoothNow: correction 3 — setter form setFrameNow(v); return v (no bare
  return (_frameNow = raw))
- _applyNoteCamTargets callers: 2 sites (7940/9923); correction 2 verified
- lookaheadSmoothCamStep callers: 3 sites (9963/9974/9978); correction 2 verified
- plugin.json: bump 3.50.0 → 3.51.0

Tests (16 files updated to scan renderer.js):
- highway_3d_renderer.test.js: new, 15 tests — export contract, DI count
  (241), tombstone, caller-list corrections, smoothNow semantics, ordering
- highway_3d_arp_deferral.test.js: add renderer.js scan (deferChordGems /
  noteStreamCoversArpShape moved to renderer.js)
- highway_3d_lean_sustain.test.js: add renderer.js scan; update to
  setLeanSus/getLeanSus() getter form
- highway_3d_smooth_clock_pause.test.js: fix literal-newline syntax error;
  update to setClkAudioT/setClkPerf/setFrameNow setter form;
  update new-sample regex to match getClkAudioT()
- highway_3d_slide_target.test.js: add renderer.js to src scan
- highway_3d_sustain_rail.test.js: assert against rendererSrc (pattern
  moved from U-section)
- highway_chart_transform.test.js: add utils.js scan (_openStringPitchLabels-
  ForTuning moved to src/utils.js by h3d-carve-3)
- highway_note_state.test.js: add renderer.js scan (_ndGetNoteState /
  _ndHasProvider captures in renderer.js update())
- highway_3d_camera_bootstrap.test.js: setter form for camSnapped/curX/
  measureStarts; renderer.js added to scan
- highway_3d_camera_framing.test.js: renderer.js added; setMeasureStarts/
  setCamSnapped setter form in assertions

Suite: 1395/1396 (test 46 pre-existing failure unrelated to carve-15)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014uZ169yfoFYArXz962g7KW

tests/js/highway_3d_smooth_clock_pause.test.js

@@ -20,6 +20,7 @@ const path = require('node:path');
 
 const highwayJs = path.join(__dirname, '..', '..', 'static', 'highway.js');
 const highway3dJs = path.join(__dirname, '..', '..', 'plugins', 'highway_3d', 'screen.js');
+const RENDERER_JS = path.join(__dirname, '..', '..', 'plugins', 'highway_3d', 'src', 'renderer.js');
 
 // Brace-balanced extraction (same helper shape as highway_note_state.test.js).
 function extractBlock(src, signature) {
@@ -60,7 +61,7 @@ test('core _makeBundle exposes isPlaying derived from the chart-clock anchor', (
 });
 
 test('smoothNow returns raw and re-anchors when the host reports not playing', () => {
-    const src = fs.readFileSync(highway3dJs, 'utf8');
+    const src = fs.readFileSync(highway3dJs, 'utf8') + '\n' + fs.readFileSync(RENDERER_JS, 'utf8');
     const fn = extractBlock(src, 'function smoothNow(bundle)');
     // Strict === false so downlevel hosts (isPlaying undefined) fall through
     // to the existing staleness-based interpolation cap.
@@ -69,14 +70,16 @@ test('smoothNow returns raw and re-anchors when the host reports not playing', (
 
     // The pause branch re-anchors the clock state and returns the raw sample
     // (no forward extrapolation).
+    // h3d-carve-15: bare assignments → DI setter calls in renderer.js
     const branch = fn.slice(guardIdx);
-    assert.match(branch, /_clkAudioT\s*=\s*raw/, 'pause branch must re-anchor _clkAudioT to raw');
-    assert.match(branch, /_clkPerf\s*=\s*p/, 'pause branch must re-anchor _clkPerf to now');
-    assert.match(branch, /return\s*\(\s*_frameNow\s*=\s*raw\s*\)/, 'pause branch must return raw');
+    assert.match(branch, /setClkAudioT\s*\(\s*raw\s*\)/, 'pause branch must re-anchor _clkAudioT to raw');
+    assert.match(branch, /setClkPerf\s*\(\s*p\s*\)/, 'pause branch must re-anchor _clkPerf to now');
+    assert.match(branch, /setFrameNow\s*\([^)]+\)/, 'pause branch must call setFrameNow (return raw)');
 
     // The pause gate must come before the new-sample re-anchor / interpolation
     // path so a frozen clock never extrapolates forward.
-    const newSampleIdx = fn.search(/if\s*\(\s*raw\s*!==\s*_clkAudioT\s*\)/);
+    // h3d-carve-15: _clkAudioT accessed via getClkAudioT() getter in renderer.js
+    const newSampleIdx = fn.search(/if\s*\(\s*raw\s*!==\s*(?:_clkAudioT|getClkAudioT\s*\(\s*\))\s*\)/);
     assert.ok(newSampleIdx !== -1, 'smoothNow new-sample branch not found');
     assert.ok(guardIdx < newSampleIdx, 'isPlaying pause gate must precede the interpolation path');
 });