docs: update README for v0.5.0 — types, recall, adaptive triggers, secret scan

fix: TDZ bug in adaptive counter, spec consistency fixes

chore: bump version to v0.5.0 — memory types, recall, freshness, secret scan, adaptive triggers, agent memory

skill(compaction): agent memory — read/write AGENT.md for learned patterns

feat: agent scope memory — spec, directory creation in init

skill(core): adaptive compaction triggers — multi-condition trigger, counter increment on checkpoint

feat(compact): adaptive counters in .compaction-state.json — rawLines and checkpoints tracking

skill(compaction): secret scan awareness in LLM summarization

feat(compact): secret scanner — redact API keys, tokens, passwords in compaction nodes

spec: freshness tracking — age calculation in root compaction, verification markers

skill(compaction): Step 0 pre-compaction WORKING.md snapshot

feat: structured WORKING.md with Key Files, Decisions, Errors, Next Steps

feat(init): install hipocampus-recall skill

skill(recall): selective recall with ROOT.md triage, manifest LLM selection, freshness warnings

skill(compaction): type-aware rules, keyword extraction, exclusion filtering, age calculation