build: remove unused :ammolite module

The :ammolite module contained no production Kotlin/Java sources (just
a manifest, build.gradle, and proguard stubs) and no module in the
codebase imports com.vitorpamplona.ammolite.*.

Removes:
- ammolite/ directory (5 files)
- :ammolite project include in settings.gradle
- implementation project(':ammolite') from :amethyst
- androidTestImplementation project(':ammolite') from :benchmark
- :ammolite:testDebugUnitTest from CI workflow and pre-push hook
- -keep class com.vitorpamplona.ammolite.** rules from
  :amethyst, :commons, and :desktopApp proguard files
- Stale references in CONTRIBUTING.md, CLAUDE.md, and the
  gradle-expert skill dependency-graph doc

Small build-graph win: one fewer module to configure, compile, lint,
and spotless-check on every build, and one fewer unit-test target in
both CI and the local pre-push hook.

.claude/skills/gradle-expert/references/dependency-graph.md

@@ -8,13 +8,13 @@
 │                     (Amethyst)                           │
 └─────────────────────────────────────────────────────────┘
                           │
-         ┌────────────────┼────────────────┬────────────┐
-         │                │                │            │
-         ▼                ▼                ▼            ▼
-┌─────────────┐  ┌─────────────┐  ┌─────────────┐  ┌──────────┐
-│  :amethyst  │  │ :desktopApp │  │ :benchmark  │  │:ammolite │
-│  (Android)  │  │   (JVM)     │  │  (Android)  │  │ (Support)│
-└─────────────┘  └─────────────┘  └─────────────┘  └──────────┘
+         ┌────────────────┼────────────────┐
+         │                │                │
+         ▼                ▼                ▼
+┌─────────────┐  ┌─────────────┐  ┌─────────────┐
+│  :amethyst  │  │ :desktopApp │  │ :benchmark  │
+│  (Android)  │  │   (JVM)     │  │  (Android)  │
+└─────────────┘  └─────────────┘  └─────────────┘
        │                │                │
        │                │                │
        └────────────────┼────────────────┘
@@ -77,7 +77,7 @@
 **Type:** Android Application
 **Targets:** Android
 **Dependencies:**
-- Modules: `:commons`, `:quartz`, `:ammolite`
+- Modules: `:commons`, `:quartz`, `:nestsClient`
 - External: Android SDK, AndroidX, Firebase, Tor
 
 **Role:** Android-specific navigation, layouts, and entry point
@@ -91,13 +91,6 @@
 
 **Role:** Performance benchmarking for Android builds
 
-### :ammolite (Support Module)
-**Type:** Android Library
-**Targets:** Android
-**Dependencies:** Android-specific utilities
-
-**Role:** Android support utilities for amethyst
-
 ## Dependency Flow Patterns
 
 ### Desktop Build Chain
@@ -112,10 +105,10 @@
 ### Android Build Chain
 ```
 :amethyst → :commons (androidMain) → :quartz (androidMain)
-    ↓                                      ↓
-:ammolite                            jvmAndroid
-                                         ↓
-                                   commonMain
+                                           ↓
+                                     jvmAndroid
+                                           ↓
+                                     commonMain
 ```
 
 ## Source Set Dependencies