chore: land janitor round 1 and graft integration

Round 1 findings and fixes, all previously uncommitted:
- FXProcessor per-slot DSP history repair (HEAD does not compile without it)
- SynthVoice::getModulationValue, editor control-lock guard
- ExactCompare.h naming the deliberate exact float comparisons
- KnobLookAndFeel replacing the never-installed SerumLookAndFeel
- 55 first-party compiler warnings to 0
- AGENT.md renamed to AGENTS.md across Source/
- graft repository context graph and its hooks
- JANITOR_TASKS.md and UI_UX_AUDIT.md records

AUDIT_REPORT.md

@@ -120,9 +120,9 @@ The Windows cross-build does not build or run tests: `build_windows.sh:50` passe
 There is no clean step in `build_windows.sh`. The script configures into `build_windows/`
 and builds without removing or cleaning it first. A clean rebuild is not scripted; it would
 require manually removing `build_windows/` (or invoking Ninja's clean target, which the
-script does not do). A combined "clean build + run tests" command does not exist: the
-Windows script disables tests, and the README test instructions assume an already-built
-native `build/` tree.
+script does not do). A combined "clean build + run tests" command does not exist.
+The Windows script disables tests, and the README test instructions assume an
+already-built native `build/` tree.
 
 ---
 
@@ -138,7 +138,7 @@ generic synth architecture.
 
 - `Params.h`/`Params.cpp` depend only on `<JuceHeader.h>` (`Params.h:3`). It declares the
   `ids`, `maps` namespaces, all enums, `ModSource`/`ModTarget`, and the wavetable name
-  table. It is the shared foundation: nearly every other file includes it.
+  table. It is the shared foundation. Nearly every other file includes it.
 - `Wavetable`, `Oscillator`, `SubOscillator`, `NoiseOscillator`, `Envelope`, `LFO`,
   `Filter`, `FilterBank`, `SynthVoice` depend only on `Params`, `JuceHeader`, and each
   other (`Oscillator.h:4-5`, `FilterBank.h:4-5`, `SynthVoice.h:4-12`).
@@ -244,7 +244,7 @@ generic synth architecture.
 
 The code intends to allocate only at prepare time, but it does not fully achieve this:
 
-- Prepare-time allocation is the norm: delay lines and buffers are sized in `prepare()`
+- Prepare-time allocation is the norm. Delay lines and buffers are sized in `prepare()`
   (`Filter.cpp:24`, `Chorus.cpp:9-11`, `Reverb.cpp:17-33`, `Engine.cpp:68`).
 - Violation 1: `Engine::processBlock` calls `mixBuffer.setSize (2, n, false, false, true)`
   on every block at `Engine.cpp:211`. `AudioBuffer::setSize` is a no-op when the size is
@@ -283,7 +283,7 @@ mix of asserts, null guards, and return codes.
   itself. The only reporting is the test harness printing to `std::cout` and returning an
   exit code (`TestMain.cpp:73,103,129,132-134`).
 
-Net style: programmer errors use `jassert` (very sparingly), runtime/state errors use null
+Net style: programmer errors use `jassert` (sparingly), runtime/state errors use null
 guards or default values, and bounded-insertion failures use `bool` return codes that
 callers currently ignore.
 
@@ -317,9 +317,9 @@ thread:
   thread reads the same `shapeBuffer` in `LFO::shapeValue` (`LFO.cpp:82-91`).
 
 None of these shared collections are locked or double-buffered. This is a real data race
-today: resizing `connections` while the audio thread iterates it is undefined behaviour.
+today. Resizing `connections` while the audio thread iterates it is undefined behaviour.
 
-The processor header acknowledges GUI-thread access but does not address the race: the
+The processor header acknowledges GUI-thread access but does not address the race. The
 comment "Public DSP state (read/write from the GUI thread)" at `PluginProcessor.h:55` only
 describes intent.
 
@@ -372,7 +372,7 @@ describes intent.
 
 ## 7. Anti-pattern catalog
 
-Each entry lists the location, the problem, and the standard that a later AGENT.md phase
+Each entry lists the location, the problem, and the standard that a later AGENTS.md phase
 should encode.
 
 1. Parameter ID tables duplicated three times.