docs: update stale entry docs and deprecate superseded docs with annotations

- docs/lithosananke/README.md + ROADMAP.md: correct branch topology (no
  lithosananke branch post-split; master is the sole line), mark M7.1 as
  live, and fix build commands (kernel/Makefile, not Makefile.starkernel)
- docs/README.md: refresh current active work (Tripod = Hera/Artemis/Hestia,
  M7.1 live, StarForth v4) and flag INDEX.md as stale
- docs/INDEX.md: add dated-snapshot staleness banner
- Add TARGET-HAL / OBSOLETE / SUPERSEDED banners to stale HAL, physics,
  heartbeat, and DoE docs under docs/working/ (annotation only, no deletions)

docs/working/experiments/02-experiments/heartbeat-doe/corrected-design.md

@@ -1,4 +1,8 @@
 <!-- Moved from docs/02-experiments/heartbeat-doe/corrected-design.md to docs/working/experiments/02-experiments/heartbeat-doe/corrected-design.md on 2026-06-16 (docs reorg Phase 2) -->
+
+> **⚠ SUPERSEDED (flagged 2026-10-09).** Superseded by `phase2-corrected.md` (the
+> "corrected and finalized" revision). Kept for historical record.
+
 # StarForth Heartbeat DoE – CORRECTED Design (Heartrate Focus)
 
 **Date:** November 20, 2025

docs/working/experiments/02-experiments/heartbeat-doe/design.md

@@ -1,4 +1,9 @@
 <!-- Moved from docs/02-experiments/heartbeat-doe/design.md to docs/working/experiments/02-experiments/heartbeat-doe/design.md on 2026-06-16 (docs reorg Phase 2) -->
+
+> **⚠ SUPERSEDED (flagged 2026-10-09).** Pre-correction draft; superseded first by
+> `corrected-design.md`, then by `phase2-corrected.md` (the finalized design). Kept for
+> historical record.
+
 # StarForth Factorial DoE with Heartbeat Integration
 
 **Date:** November 20, 2025