feat(windows): embed Bloom in a host window via bloom_attach_hwnd (Perry UI BloomView, #2395)

[proggeramlug]

The engine side of the Perry UI BloomView widget (PerryTS/perry#5518) — lets Bloom render into a host-provided window instead of always creating its own top-level window, so it can live as a render view inside a normal Perry UI app (analogous to Flame inside Flutter). Pairs with perry-issue #2395.

Changes

• native/windows/src/lib.rs: factor the wgpu surface + engine init out of bloom_init_window into init_engine_for_hwnd, shared with a new FFI:
  • bloom_attach_hwnd(hwnd, w, h) — build the surface on a host-provided HWND and classic-subclass it so Bloom still sees WM_SIZE / keyboard / mouse (its own wndproc never runs for a foreign-class window), then chain to the original proc.
  • bloom_resize(physW, physH, logW, logH) — explicit resize.
  • An EMBEDDED flag: bloom_begin_drawing skips its own message pump (the host owns the loop) and bloom_window_should_close reports "stay open".
• src/core/index.ts: attachToHwnd / resize TS wrappers (re-exported from src/index.ts).
• package.json: declare bloom_attach_hwnd / bloom_resize in the native-library function manifest so Perry links them.
• embed-perry/: a demo Perry UI app that embeds a live Bloom 3D scene.

Usage

import { BloomView, bloomViewGetHwnd } from 'perry/ui';
import { attachToHwnd, beginDrawing, endDrawing, clearBackground /* … */ } from 'bloom';

const view = BloomView(820, 480);
let attached = 0;
setInterval(() => {
  if (!attached) { attachToHwnd(bloomViewGetHwnd(view), 820, 480); attached = 1; }
  beginDrawing(); clearBackground({ r: 18, g: 22, b: 34, a: 255 }); /* …draw 3D… */ endDrawing();
}, 16);

The host owns the message loop, so drive frames yourself (don't call runGame, which blocks).

Status

• Windows only. Per-platform attach (NSView / UIView / GTK4 dmabuf) is a follow-up; the Perry-side BloomView widget already links on all targets.
• Verified end-to-end: the embed-perry/ demo compiles and renders a live, animating 3D scene inside a Perry UI window, including resize (see embed-perry/bloomFull.png).
• The demo requires the BloomView Perry build from feat(ui): BloomView — embed the Bloom engine in a Perry UI app (#2395) PerryTS/perry#5518 to compile/run.

🔗 Perry-side PR: PerryTS/perry#5518