Port Resvg bbox, crop, render, and external-buffer corpus

Track the contiguous Bun corpus blocker at js/third_party/resvg/bbox.test.js (position 4048).

Required parity:

• load @resvg/resvg-js through the corpus module bridge;
• parse SVG view boxes and preserve intrinsic width/height;
• expose getBBox(), cropByBBox(), render(), and asPng() behavior for the copied transformed-path fixture;
• preserve JavaScript subclass construction and methods;
• exercise repeated PNG external-buffer creation plus GC without crashes or retained aliases;
• emit structured causal parse/render diagnostics that identify the operation without embedding SVG source data.

Implemented and pushed in https://github.com/home-lang/home/commit/4ea6295f3.

Coverage now includes:

• @resvg/resvg-js loading through the corpus module bridge;
• SVG view-box parsing and intrinsic width/height;
• the copied transformed heart-path bbox, stroked-use bounds, bbox cropping, width fitting, and rendered dimensions;
• normal JavaScript subclass construction/method preservation;
• fresh PNG buffer allocation across repeated render/GC cycles;
• ResvgError parse/crop/render failures with stable operation-specific codes, retained causes, explicit operation frames, and no SVG source in messages or stacks.

Verification:

• focused position 4048: 1 file, 3 passed, 0 failed/todo/unsupported/allowed-empty;
• positions 4047–4048: 2 files, 4 passed, 0 failed/todo/unsupported/allowed-empty;
• permanent gRPC error-stack, SQL adapter-contract, and 31-case third-party diagnostic suites all pass.