fix: install.sh finds binary under custom target triples

Nightly toolchains with CARGO_BUILD_TARGET set (or .cargo/config.toml
[build] target) put the binary in target/<triple>/release/ instead of
target/release/. The installer now falls back to a find search across
all target subdirectories when the standard path doesn't exist.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

install.sh

@@ -40,10 +40,16 @@ if ! (cd "$SCRIPT_DIR" && cargo build --release); then
   exit 1
 fi
 
+# Find the binary — handles custom target triples (e.g., CARGO_BUILD_TARGET
+# puts it in target/<triple>/release/ instead of target/release/)
 BINARY="$SCRIPT_DIR/target/release/$BINARY_NAME"
 if [[ ! -f "$BINARY" ]]; then
-  echo "ERROR: Build succeeded but binary not found at $BINARY"
-  echo "  Check: ls $SCRIPT_DIR/target/release/"
+  BINARY=$(find "$SCRIPT_DIR/target" -name "$BINARY_NAME" -type f -path "*/release/*" ! -name "*.d" 2>/dev/null | head -1)
+fi
+if [[ -z "${BINARY:-}" || ! -f "$BINARY" ]]; then
+  echo "ERROR: Build succeeded but binary not found."
+  echo "  Searched: $SCRIPT_DIR/target/*/release/$BINARY_NAME"
+  echo "  Contents: $(ls "$SCRIPT_DIR/target/release/" 2>/dev/null || echo '(no target/release/)')"
   exit 1
 fi
 echo "[ok] Built: $(ls -lh "$BINARY" | awk '{print $5}')"