Phase 535: refresh post-lasso visual feedback parity queue

[ExplodingUFO]

Context

Phase 534 closed the transient lasso visual gesture feedback route. The bilingual React Flow parity roadmap still lists Phase 534 as the current active row and does not yet select the next bounded whiteboard/parity follow-up from the remaining gaps.

Scope

Refresh the parity roadmap and focused docs tests after Phase 534 so the next implementation slice is tracker-backed and current.

Proposed follow-up queue

• Phase 536: lasso screenshot route and Cookbook proof boundary.
• Phase 537: lasso toolbar UX / public activation ergonomics boundary.
• Phase 538: eraser behavior/API feasibility or first bounded eraser contract.
• Phase 539: rectangle/freehand drawing primitive model gate.
• Phase 540: whiteboard persistence/render layer gate.

Acceptance Criteria

• English and Chinese parity roadmap record Phase 535 with this GitHub issue and Bead ID.
• The next issue wave no longer marks Phase 534 as current active work.
• Remaining whiteboard/parity gaps are split into concrete candidates with priority, likely write set, dependencies, and parallelism notes.
• Focused docs tests guard the post-Phase-534 queue and stale-row removal.
• Scope explicitly forbids runtime behavior changes, public API changes, UI redesign, screenshot manifest expansion, strict pixel baseline enforcement, retained API removal, and whiteboard implementation.

Verification

• Focused ReactFlowParityRoadmapDocsTests pass.
• git diff --check passes.
• Build or targeted test pass is recorded.