[P2] Polish batch: archive-only buffers, memory-layout citation, test-count drift, keywords

[jsirish]

From docs/AUDIT-v0.4.0.md (P2, item 10). Four small items, one PR:

1. handoff SKILL.md Phase 4.4 says "move ... into archive/ (or delete)" - drop "or delete"; archive-only removes an unguarded data-loss affordance.
2. handoff Phase 4.3 (memory binding) should cite the now-documented native auto-memory layout (MEMORY.md index loaded at 200 lines/25KB, topic files on demand, ~/.claude/projects//memory/) and include a one-line frontmatter example inline, so an executing model can't produce malformed entries.
3. Test-count drift: CHANGELOG 0.3.0 says 88, 0.2.0 says 71, the repo's own HANDOFF said 83. Current truth is 95 (post-0.4.1). Add a single source of truth (the suite prints its own count; stop hardcoding it in prose, or say "95 as of 0.4.1" style with version anchor).
4. plugin.json keywords under-sell the differentiators: add git-state, cross-harness/portable, resume, onboarding.