refactor: Container-only builds for consistency

- Remove --no-container option (never build on real host)
- Simplify build.sh to always use containers
- Fix Dockerfile user permissions
- Update help text and argument parsing
- Pass arguments correctly to container builds

Dockerfile

@@ -27,12 +27,12 @@ RUN apk add --no-cache \
 # Install musl-dev for Rust musl targeting (Alpine handles this differently than rustup)
 RUN apk add --no-cache musl-dev
 
-# Create non-root user for builds
-RUN adduser -D -s /bin/bash builder && \
-    chown -R builder:builder /home/builder
+# Create non-root user for builds matching host user
+RUN adduser -D -s /bin/bash builder
 
-# Set working directory
+# Set working directory with proper permissions
 WORKDIR /workspace
+RUN chown builder:builder /workspace
 
 # Set environment variables for musl static linking with Alpine's Rust
 ENV RUSTFLAGS="-C target-feature=+crt-static -C linker=musl-gcc"
@@ -40,7 +40,6 @@ ENV CC="musl-gcc"
 ENV TARGET_CC="musl-gcc"
 ENV CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER="musl-gcc"
 
-# Default to builder user
-USER builder
+# Don't switch to builder user yet - let the runtime handle it
 
 CMD ["/bin/bash"]