Introduce a single-threaded wasm build mode and add defensive runtime handling for missing wasm threading support.
- CLI: add --no-threads flag and WasmConfig.threads to control threaded vs single-threaded builds. Parse and strip wasm-specific options before forwarding build/run args.
- Build: select target features and RUSTFLAGS based on threading; omit atomics/bulk-memory features for single-threaded builds. Adjust generated server instructions to require COOP/COEP only for threaded builds.
- Dev server: conditionally include COOP/COEP headers when serving threaded wasm artifacts.
- JS runtime (platform/src/os/web/web.js): guard audio worklet startup and thread creation on wasm._has_thread_support; make alloc_thread_stack return null with clear console warnings when required exports or alignment are missing; pass allocated thread_info to workers.
These changes enable building and running a single-threaded wasm variant without COOP/COEP server requirements and improve runtime resilience when threading features are unavailable.
Rename AlignEntry::BeginTurtle/EndTurtle to BeginClip/EndClip — these
entries control GPU clip rect stacking, not turtle lifecycle.
Add push_clip_rect/pop_clip_rect to Cx2d: lightweight API for manual
clip rect control without creating a full turtle. The existing
clip_and_shift_align_list pass intersects nested clip rects and writes
draw_clip into draw call instances.
Co-authored-by: ant <ant@offline.click>
Add Texture::set_data_u32(cx, width, height, data) that replaces pixel
data and dimensions in one call. Unlike put_back_vec_u32, this also
updates width/height, making it safe for image sources that change
resolution (animated images, lazy-loaded placeholders).
Co-authored-by: ant <ant@offline.click>
