v9.97 - Context Load and Document Density Control

Summary

• Adds context-load-and-document-density-control.md as the 47th source-owned active runtime rule.
• Defines leader-context protection, worker-first broad evidence filtering, aggregate read-burst awareness, God-line prevention, append-vs-restructure gates, and compact/thrash repair signals.
• Syncs README, design, changelog, TODO, phase, and patch records for P090 / v9.97.

Verification

• README Bash and PowerShell install arrays matched at 47/47 active runtime rules.
• Runtime install copied only the 47 README-listed source-owned active runtime rules.
• Source/runtime hash parity and active runtime body sufficiency passed for 47/47 files.
• Touched active docs passed density review after P090 row and table compaction.