fix(android): PATH wrapper to redirect tauri-cli's android24-clang → android26

Build #12's instrumented pthread_shim gave us the definitive diagnosis:

  WZP_pthread_shim: dlsym(RTLD_DEFAULT, pthread_create) returned NULL:
    libdl.a is a stub --- use libdl.so instead

Tauri-cli invokes `aarch64-linux-android24-clang` as the linker and the
API-24 NDK sysroot ships *stub* libdl.a / libc.a: they compile fine but
every symbol crashes if called, because they're meant to coexist with a
separate dynamic .so that the dynamic linker provides at runtime. Rust's
pre-built libstd.rlib has static calls into those stubs baked in, so no
matter what we do at link time the broken code lands in the .so.

Env-var overrides of CARGO_TARGET_AARCH64_LINUX_ANDROID_LINKER don't
stick — tauri-cli resets them before invoking cargo. So instead of
fighting the env, we put a wrapper on $PATH, literally named
`aarch64-linux-android24-clang`, that exec()s the android26 version.
When tauri-cli looks up android24-clang via PATH, it gets our wrapper,
our wrapper runs android26-clang, and suddenly the whole build is using
the API-26 NDK sysroot with real dynamic bindings to libc.so / libdl.so.

Wrappers are installed for all four ABIs (aarch64, armv7, x86_64, i686)
× both suffixes (clang, clang++) directly inside the docker bash -c
preamble before any cargo invocation.

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

scripts/build-tauri-android.sh

@@ -166,6 +166,30 @@ docker run --rm \
     wzp-android-builder \
     bash -c '
 set -euo pipefail
+
+# ─── Linker wrappers ───────────────────────────────────────────────────────
+# Tauri-cli hard-codes aarch64-linux-android24-clang as the Rust linker for
+# the aarch64 target, which resolves pthread_create / dlsym / __init_tcb
+# against the NDK API-24 *stub* libc.a/libdl.a. Those stubs are designed to
+# crash if called — they only exist so the API-24 sysroot compiles, not so
+# symbols actually work. API-26 has the real dynamic bindings to libc.so.
+#
+# Rather than fight tauri-cli to change which clang it invokes, we put a
+# wrapper on $PATH that IS named android24-clang but exec()s the android26
+# version. Same trick works for every ABI.
+mkdir -p /tmp/wrappers
+for abi in aarch64-linux-android armv7a-linux-androideabi i686-linux-android x86_64-linux-android; do
+    for suffix in clang clang++; do
+        cat > /tmp/wrappers/${abi}24-${suffix} <<WRAPPER
+#!/bin/sh
+exec /opt/android-sdk/ndk/26.1.10909125/toolchains/llvm/prebuilt/linux-x86_64/bin/${abi}26-${suffix} "\$@"
+WRAPPER
+        chmod +x /tmp/wrappers/${abi}24-${suffix}
+    done
+done
+export PATH=/tmp/wrappers:$PATH
+echo ">>> installed android24→android26 linker wrappers in /tmp/wrappers"
+
 cd /build/source/desktop
 
 echo ">>> npm install"