fix(lod): stabilize distant transition and chunk coverage

[MichaelFisher1997]

Summary

• replace screen-space Bayer LOD transition dither in G-pass with world-space noise to avoid distant static/pixel-dot artifacts
• require a 1-chunk halo when deciding whether to hide LOD regions behind fully loaded block chunks
• keep this PR scoped to non-shadow changes only (shadow-system refactor tracked separately in [HIGH] Stabilize sun shadows on LOW preset (camera-angle morphing) #278 and [HIGH] Refactor shadow architecture: decouple visual LOD from shadow casters #279)

Validation

• pre-push checks passed
• nix develop --command zig build test

Notes

• this branch still has local uncommitted shadow-work changes that are intentionally not included in this PR commit set

[opencode-agent]

📋 Summary

This PR addresses LOD rendering issues by replacing screen-space Bayer dithering with world-space noise to eliminate distant artifacts, and implementing a 1-chunk coverage halo to prevent exposing cut-faces at LOD transitions. The changes are focused and well-scoped to non-shadow systems as intended. All tests pass including shader validation.

🔴 Critical Issues (Must Fix - Blocks Merge)

None identified.

⚠️ High Priority Issues (Should Fix)

None identified.

💡 Medium Priority Issues (Nice to Fix)

None identified.

ℹ️ Low Priority Suggestions (Optional)

None identified.

📊 SOLID Principles Score

Principle	Score	Notes
Single Responsibility	9	Changes are focused on specific LOD rendering concerns
Open/Closed	9	New noise function extends without modifying existing logic
Liskov Substitution	10	No inheritance changes, interface compatibility maintained
Interface Segregation	9	GPU bridge pattern maintains clean separation
Dependency Inversion	9	Abstracted chunk checking through callbacks
Average	9.2

🎯 Final Assessment

Overall Confidence Score: 92%

Confidence Breakdown:

• Code Quality: 95% (Clean implementation, follows project conventions)
• Completeness: 90% (Achieves stated goals, well-scoped)
• Risk Level: 85% (Low risk - shader change is isolated, padding logic is straightforward)
• Test Coverage: 95% (Tests pass, includes unit tests for affected components)

Merge Readiness:

• All critical issues resolved
• SOLID average score >= 6.0
• Overall confidence >= 60%
• No security concerns
• Tests present and passing (if applicable)

Verdict:

MERGE

The PR successfully implements both fixes with clean, well-tested code that follows project conventions. The world-space noise function in g_pass.frag is properly documented and eliminates the Bayer dithering artifacts, while the 1-chunk padding in both lod_manager.zig and lod_renderer.zig correctly addresses the cut-face exposure issue at LOD boundaries.

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