chore: checkpoint web Blender migration source, tools and docs

Accumulated uncommitted work: GHOST Web backend, WebGL/GPU web layer,
web workflow engine and protocol, tooling, docs and task records.
Large generated evidence, user-testing archives, build snapshots and
imported test assets remain untracked.

Co-Authored-By: Claude Code <noreply@anthropic.com>

docs/tasks/WBV2-P809-002.md

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+# WBV2-P809-002: implement_capability_family_slice
+
+- task: WBV2-P809-002
+- parent: WBV2-P809-001
+- status: planned
+- gap: workflow:implement_capability_family_slice
+- ownerFamily: IMPLEMENTATION
+- targetImplementationClass: SOURCE_BACKED
+
+## 目标
+
+Implement the next uncovered Blender capability family from the source-backed index.
+
+## 输入与范围
+
+- Blender source authority: `blender-5.2.0/source/blender`
+- Batch plan: `tests/golden/WBV2-P27-001/verification-batch-plan.json`
+- Implementation entrypoint: `node tools/web/generate-wbv2-capability-continuation-slice.mjs --task WBV2-P809-002 --write`
+
+## 验收
+
+- 6900 inventory and provenance remain read-only
+- capability-family deduplication is reused
+- malformed, unsupported, hash-drift and false-completion input fails closed
+- Chromium, E2E receipts and completion overlays remain deferred
+- `node tools/web/check-task-context.mjs --task WBV2-P809-002 --write`
+
+## 失败边界
+
+- missing source or unsupported capability remains in_progress/blocked
+- representative implementation is never declared as full-family parity
+
+## 交付与回滚
+
+- Reports: `tests/golden/WBV2-P809-002/`
+- Status: `docs/status/WBV2-P809-002.md`
+- Manifest: `tests/golden/WBV2-P809-002/manifest.json`
+- Rollback: restore WBV2-P809-001 as queue parent and leave the task in_progress.