docs: Prune documentation - DRY versioning, split roadmap

- Split roadmap into dedicated ROADMAP.md (links to phoebe tasks)
- Prune Endgame-Vision.md: roadmap section, links section, version history
- Standardize version footers: one-line format across 17+ files
- Add Navigation section pointing to README.md for file index

Pattern: **Version:** X.Y | **Created:** YYYY-MM-DD | **Updated:** YYYY-MM-DD

Git is the changelog. Philosophy quotes preserved.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

architecture/Initial-Spark.md

@@ -724,10 +724,7 @@ WHERE status = 'ACK';
 
 ## Document Status
 
-**Version**: 3.0
-**Created**: 2025-12-05
-**Updated**: 2026-01-01 (Complete rewrite: Function Gemma K8s protocol)
-**Authors**: Chrysalis-Nyx & dafit (Partnership)
+**Version:** 3.0 | **Created:** 2025-12-05 | **Updated:** 2026-01-01
 
 **Key v3.0 Changes**:
 - Complete architecture rewrite