Generic synth name, calmer knobs, darkwave/industrial presets (v0.5.0)

- Rename the 3-osc synth's display name "NES Synth" → "Synth" (the enum
  NES_SYNTH stays as the serialized id, so saved projects/presets are
  unaffected).
- Knobs: replace absolute finger-position control (full range mapped onto
  the 44dp knob → very touchy) with relative drag over ~280dp of travel,
  so fine tweaks are easy and the control isn't sensitive.
- Add a darkwave/industrial preset family: Pluck Bass, Acid Pluck
  (punchy plucky basses), Razor Lead, Cold Lead (cutting leads), and
  Grit Sub, Detune Wall (harsh, detuned deep basses for layering under
  bass pads).
- Preset seeding now records seeded names in the per-type marker instead
  of a single flag, so factory presets added in a later version appear on
  upgrade without resurrecting presets the user deleted (legacy "1"
  markers upgrade cleanly).

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 = 14
-        versionName = "0.4.7"
+        versionCode = 15
+        versionName = "0.5.0"
 
         // We provide our own instrumentation runner if/when tests are added.
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"