Add Chromium-only Blender WebEngine parity work

docs/status/W-078.md

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+# W-078 Status
+
+status: in_progress  
+task: 轻量化预算和导出策略
+
+`protocol/budget.ts` now validates explicit integer budgets for triangles,
+vertices, index bytes, material slots, texture bytes and estimated GPU bytes.
+`evaluateLightweightBudget` returns every violation with limit, actual value and
+excess while leaving the measured usage unchanged. Browser E2E covers a mixed
+triangle/GPU over-budget report.
+
+`aggregateLightweightUsage` and `evaluateLightweightBudgets` now produce
+deterministic project, collection, object and LOD scopes. Project usage sums
+each source object once; collection membership is reported per collection and
+LOD usage is kept separate so generated levels are not double-counted. Browser
+E2E covers all four scope reports.
+
+`analyzeGLBExport` now runs before the UI export action and returns structured
+warnings/errors for summary-only or missing geometry, unevaluated modifiers,
+external/packed images, linked material inputs and unavailable skin remapping.
+When no blocking condition is present, the local exporter writes a standards-
+shaped GLB 2.0 binary containing hierarchy, mesh positions/normals/UVs/colors,
+material groups, PBR material factors and shape-key morph targets. Blender
+shape-key positions are converted to glTF deltas in the Z-up to Three.js/glTF
+basis conversion. The top-bar action downloads this local binary; browser E2E
+checks the GLB header and a non-zero morph delta.
+
+`exportGLB` now accepts caller-provided local asset buffers, embeds each image
+as a GLB buffer view, and connects it to exported PBR materials. It exports
+`JOINTS_0`/`WEIGHTS_0`, bone nodes, inverse bind matrices and supported object
+or bone animation channels for a resolved armature binding. The local test
+worker parses the emitted GLB JSON again; browser E2E embeds a real local PNG
+and verifies its byte length/signature, skin joints, MAT4 inverse-bind accessor,
+animation channels and skin attributes without a network fetch.
+
+The native reader now extracts the exact bytes of both legacy and list-based
+Blender packed images through the local asset request ABI; the packed fixture
+checks PNG signature, MIME and byte length without a network request. The GLB
+worker strictly parses the emitted JSON/BIN chunks and compares mesh
+attributes, embedded image byte counts/MIME, skin joints/inverse-bind MAT4s,
+morph targets and grouped animation paths against the source SceneIR. The
+browser round-trip test has no semantic mismatches. Blender-side unsupported
+features remain explicit export warnings.