Document Rendering Strategy & Rollback #791

Summary

Update docs to reflect Phaser-native rendering, test strategy, and branch-based rollback guidance.

Player and user experience impact

• Player experience: Card visuals remain visible and correctly occluded by overlays using Phaser layer/depth semantics.
• Developer experience: One consistent rendering path with reduced DOM-specific maintenance overhead.

Acceptance Criteria

• Documentation reflects no-DOM runtime policy and final rendering architecture.
• Test strategy docs describe canvas-native layering assertions.
• Worklog notes include branch/commit traceability and rollback approach.

Minimal Implementation (end-to-end slice)

• Update docs/main-street/prd-milestone-4.md and related developer docs.
• Add concise rollback guidance referencing dedicated branch/revert process.
• Record changed files and rationale in Worklog comment.

Dependencies

• Remove SvgDomRenderer Dead Code

Deliverables

• Doc updates
• Worklog handoff note

References

• Parent: Phaser-native rendering for DOM SVG card visuals (replace svgDom) (CG-0MP8YFNX4007N9ZU)