feat(attach): host-surface attach path on all platforms (PerryTS/perry#5519)

[proggeramlug]

Follow-up to PerryTS/perry#5519 (BloomView live rendering) and the Windows-side bloom_attach_hwnd work (#70). Adds a per-platform attach-to-a-host-provided-surface entry point so a Perry UI BloomView can hand the engine a native view/window/surface it already owns, instead of the engine creating its own window.

What

A single unified ABI symbol — bloom_attach_native(handle, width, height) -> f64 — exported by every platform, each interpreting handle as its own native pointer. (Chosen over distinct bloom_attach_nsview/uiview/surface names because the function manifest is shared and validate-ffi requires every platform to export every entry; a single symbol beats N per-platform stubs.) TS exposes the issue's named wrappers attachToNSView / attachToUIView / attachToSurface + a generic attachToNativeView, all forwarding to it.

Engine

• native/shared/src/attach.rs — factors the wgpu bring-up (instance → surface → adapter → device → swapchain → Renderer → EngineState), duplicated near-verbatim across every platform's bloom_init_window, into one attach_engine() helper. Parameterised by backend bitmask, dimensions (logical + physical for HiDPI), and a FormatPreference (Srgb / NonSrgb / First) capturing each platform's swapchain-format policy. Returns a Result instead of panicking so a host attaching to a not-yet-realized view can recover.
• macOS — bloom_init_window refactored to call attach_engine (proving the factoring) + real bloom_attach_native on a host NSView.
• iOS / tvOS / visionOS — real attach on a host UIView (tvOS/visionOS use a non-sRGB swapchain to match their windowed path).
• Android — real attach on a host ANativeWindow.
• Windows — real attach on a host HWND.
• Linux — documented stub returning 0: GTK4 GtkWidget→GdkSurface bridging is the larger follow-up the issue calls out.
• watchOS — regenerated no-op stub (no wgpu). web — wasm_bindgen no-op (web builds its surface from the canvas id).
• package.json manifest entry added; validate-ffi passes 0 failures / 0 warnings across all 8 platforms.

Verification

• shared compiles (native + wasm32); macOS builds and renders a scene end-to-end headless — getScreenWidth/Height read back 320x240 from the attached EngineState, 30 frames, clean exit 0 (a failed attach .expect-panics, so this confirms the refactored bloom_init_window path).
• iOS cross-compiles clean (covers the near-identical tvOS/visionOS UIKit path); web wasm32 checks.
• Android / Linux / Windows cross-builds are blocked locally only by missing C cross-toolchains (NDK / linux-gcc / MSVC), not by this code; their attach bodies mirror each platform's existing surface block.

Perry side (not in this PR)

The Perry BloomView rename (bloomViewGetHwnd → bloomViewGetNativeHandle), per-platform sizing, Android SurfaceView, and input/focus routing tracked in PerryTS/perry#5519 are a separate change against the Perry repo.

[proggeramlug]

Rebased onto current main (picked up #69/#70) and got CI fully green (mergeStateStatus: CLEAN).

Two follow-on commits beyond the attach feature, both fixing pre-existing red on main (the ffi-parity job is non-required, so #69/#70 merged with it failing — 29 failures):

• chore(ffi) — completes the FFI-manifest contract for feat(render): clouds, foliage wind, additive fog, immediate-mode shadows, Windows fixes #69/feat(windows): embed Bloom in a host window via bloom_attach_hwnd (Perry UI BloomView, #2395) #70's new functions: real bloom_resize on every native platform (forwards to the shared Renderer::resize, so host-driven BloomView resize now works everywhere, not just Windows), no-op bloom_attach_hwnd stubs on non-Windows (HWND-specific; those hosts use bloom_attach_native), regenerated watchOS stubs, and documented web gaps. validate-ffi 29 → 0.
• chore(ci) — grandfathers renderer/mod.rs at its current 11985 lines (it grew in feat(render): clouds, foliage wind, additive fog, immediate-mode shadows, Windows fixes #69 but the ratcheting baseline was left at 11775, leaving check-file-lines red). No code change.

Verified after rebase: macOS rebuilds + renders a scene end-to-end headless (screen reads back 320x240 from the attached EngineState, 30 frames, clean exit); iOS cross-compiles.