fix: guard filter tail NaNs, skip static-filter envelope work, pin stereo filter path, correct stale comments

Codec fallback for non-finite filter fields, a modAmount==0 early-out in tickFilterCutoff,
new stereo render tests for the dual-mono mirror, and comment/test accuracy fixes flagged
in review (stale deck-width claims, restated invariants, drifted CMake link comments).

src/shell/instrument/editor_session.cpp

@@ -38,8 +38,9 @@ using util::readFileBytes;
 
 ReaSamplerEditor::ReaSamplerEditor(ReaSamplerProcessor* processor)
     : CPluginView(nullptr), processor_(processor) {
-    // Default view size, tuned to the three band heights: chrome + two-lane waveform +
-    // deck row. 840x620 clears the full face without scroll on 1080p.
+    // Default view size, tuned to the band heights: chrome + two-lane waveform + the deck
+    // (now two rows since the filter group). 840x620 clears the full face without scroll on
+    // 1080p.
     ViewRect r(0, 0, 840, 620);
     setRect(r);
 }