Mix Tightener: per-component Strength faders (EQ / Comp / Limiter) (v0.7.1)

The single Strength control becomes four faders: the master Strength plus a
per-stage trim for EQ, Compressor and Limiter. Each stage's effective amount
is master × its own fader, so you can keep the tone shaping but ease off the
compression, push only the limiter for loudness, etc. Backward compatible —
presets still set the master `strength`; the new eqAmt/compAmt/limAmt default
to 1 (full).

 * DSP (MixTightener): EQ gains scale by strength×eqAmt; compressor gain
   reduction + makeup by strength×compAmt (compActive skips the whole comp
   stage at compAmt 0); limiter ceiling + output make-up by strength×limAmt.
 * Editor: four labelled vertical faders (Strength / EQ / Comp / Limit). Fixed
   a refresh bug where a fader child composable didn't observe vm.revision, so
   its value didn't visibly update after a drag (the DSP did update); it now
   subscribes like ParamControl.

Verified on-device: dragging EQ to 19% left Strength/Comp/Limit at 100%
(independent control, UI refreshes). Test instance added on a spare slot for
verification, then cleared — project untouched.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/build.gradle.kts

@@ -22,8 +22,8 @@ android {
         // (android.media.midi) and AAudio low-latency audio we rely on.
         minSdk = 26
         targetSdk = 34
-        versionCode = 19
-        versionName = "0.7.0"
+        versionCode = 20
+        versionName = "0.7.1"
 
         // We provide our own instrumentation runner if/when tests are added.
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"