build: Android APK builds working — debug (8.9MB) and release (2.0MB)

- Fix C++ std::std:: double namespace in oboe_bridge.cpp
- Auto-fetch Oboe headers from GitHub in build.rs
- Configure cargo cross-compilation (.cargo/config.toml) with NDK linkers
- Fix Gradle settings (dependencyResolutionManagement), signing configs,
  Compose LinearProgressIndicator API, and Android manifest theme
- Add Gradle wrapper, .gitignore for build artifacts
- arm64-v8a only (raptorq crate incompatible with armv7 32-bit)
- Release APK: 2.0MB signed with wzp-release key
- Debug APK: 8.9MB signed with wzp-debug key

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/wzp-android/build.rs

@@ -1,15 +1,36 @@
+use std::path::PathBuf;
+
 fn main() {
     let target = std::env::var("TARGET").unwrap_or_default();
+
     if target.contains("android") {
-        // Real Oboe build for Android targets
-        cc::Build::new()
-            .cpp(true)
-            .std("c++17")
-            .file("cpp/oboe_bridge.cpp")
-            .include("cpp")
-            .compile("oboe_bridge");
+        // On Android, try to build with Oboe. If Oboe is not available,
+        // fall back to the stub (audio will need to be provided via JNI).
+        let oboe_dir = fetch_oboe();
+        match oboe_dir {
+            Some(oboe_path) => {
+                println!("cargo:warning=Building with Oboe from {:?}", oboe_path);
+                cc::Build::new()
+                    .cpp(true)
+                    .std("c++17")
+                    .file("cpp/oboe_bridge.cpp")
+                    .include("cpp")
+                    .include(oboe_path.join("include"))
+                    .define("WZP_HAS_OBOE", None)
+                    .compile("oboe_bridge");
+            }
+            None => {
+                println!("cargo:warning=Oboe not found, building with stub");
+                cc::Build::new()
+                    .cpp(true)
+                    .std("c++17")
+                    .file("cpp/oboe_stub.cpp")
+                    .include("cpp")
+                    .compile("oboe_bridge");
+            }
+        }
     } else {
-        // Stub for host builds / testing
+        // Non-Android: always use stub
         cc::Build::new()
             .cpp(true)
             .std("c++17")
@@ -18,3 +39,37 @@ fn main() {
             .compile("oboe_bridge");
     }
 }
+
+/// Try to find or fetch Oboe headers.
+/// Returns the path to the Oboe source root (containing include/ directory).
+fn fetch_oboe() -> Option<PathBuf> {
+    let out_dir = PathBuf::from(std::env::var("OUT_DIR").unwrap());
+    let oboe_dir = out_dir.join("oboe");
+
+    // Check if already fetched
+    if oboe_dir.join("include").join("oboe").join("Oboe.h").exists() {
+        return Some(oboe_dir);
+    }
+
+    // Try to clone Oboe from GitHub
+    let status = std::process::Command::new("git")
+        .args([
+            "clone",
+            "--depth=1",
+            "--branch=1.8.1",
+            "https://github.com/google/oboe.git",
+            oboe_dir.to_str().unwrap(),
+        ])
+        .status();
+
+    match status {
+        Ok(s) if s.success() => {
+            if oboe_dir.join("include").join("oboe").join("Oboe.h").exists() {
+                Some(oboe_dir)
+            } else {
+                None
+            }
+        }
+        _ => None,
+    }
+}