Launch step 1: merge Phase 4, add CHANGELOG + SECURITY.md, cut v0.1.0 #8

Part of #7 (step 1). Plan: docs/reviews/2026-10-24-launch-plan.md.

What: Decide the v0.1.0 scope and cut the release.

Recommendation: ship v0.1.0 from main after merging PR #6 (Phase 4). Do not wait for Phase 5 (JSONL export/import) or Phase 6 (musl/Windows binaries); move those to v0.2.0. Rationale: the branch is already verified (217 passed / 0 failed / 2 ignored; code re-review passed 28/28 per #5), its README already documents "Behavioral changes in v0.1.0", and every week of delay costs discovery time in the MCP directories while competitors with the same pitch (e.g. timgordontg/engrim) are already listed.

How:

1. Merge PR feat: Phase 4 — memory_update, typed relations, hybrid RRF search #6 (squash or merge, owner's choice); confirm CI green on main.
2. Bump version = "0.0.1" -> 0.1.0 in crates/agent-memory/Cargo.toml:3 and crates/agent-memory-core/Cargo.toml:3; run cargo update -p chacha20 (yanked 0.10.1 in Cargo.lock warned during cargo publish --dry-run).
3. Add CHANGELOG.md (Keep-a-Changelog) from git log v0.0.1..main --oneline: 97 commits, 31 code / 66 docs. Headline entries: memory_update + PATCH /api/memories/{id}; memory_link/memory_unlink (relates_to, supersedes, caused_by) with cascade and expand_links; RRF hybrid search (search_mode: "hybrid"), forgiving FTS5 query leg; migration 0003 + pre-migration backup + newer-schema refusal; exact tag match; 400 on out-of-range limit/ttl_secs; hosted-runner release pipeline with SLSA attestation (ci: release.yml targets [orangepi] on a public repo — the next release cannot be scheduled #1); REST loopback-only default with --allow-remote.
4. Add SECURITY.md (private reporting route via GitHub Security Advisories; scope: local binary, unauthenticated REST is loopback-only by design). This plus CHANGELOG closes chore: repo hygiene — no SECURITY.md, no CHANGELOG.md #2 — do not close chore: repo hygiene — no SECURITY.md, no CHANGELOG.md #2 until both land.
5. Do step 2 (Launch step 2: rename binary crate to agent-memory-mcp and publish to crates.io from CI #9, crate rename) before tagging so the tag's Cargo.toml is the one published to crates.io.
6. git tag v0.1.0 && git push origin v0.1.0 — release.yml triggers only on v[0-9]+.[0-9]+.[0-9]+ (.github/workflows/release.yml:65-66). Watch the run: this is the first tag run from an x86_64 hosted runner, the darwin zigbuild legs are hard-required and have only been proven on the old ARM64 host (comment block in release.yml).

Done when: gh release view v0.1.0 shows 4 required tarballs (+ musl if built) + SHA256SUMS.txt, attestation verifies, CHANGELOG and SECURITY.md are on main.

Effort: ~3 h (plus waiting on the release run).