docs(release-notes): curated 3.0.1 section

[bokelley]

Summary

Adds the curated Version 3.0.1 section to `docs/reference/release-notes.mdx` ahead of the cut, plus bumps the FAQ's current-version mention. Lands BEFORE the Version Packages PR (#3042) merges, so the 3.0.1 release ships with the curated narrative already on main.

Frames 3.0.1 as a stable-surface no-op for 3.0-conformant agents with an honest accounting of what did change.

What's in the 3.0.1 narrative

• Adopter action table — per-audience takeaway: production agent (nothing), SDK consumer (bump `ADCP_VERSION`), governance/TMP implementer (review additive fields), `get_signals` caller using top-level `max_results` (migrate to `pagination.max_results`)
• Why 3.0.1 exists — skills bundle in `/protocol/3.0.1.tgz`. Re-cutting at 3.0.0 would have invalidated cosign attestations bound to the original 3.0.0 SHA-256.
• Spec polish — `acquire_rights` validation MUSTs, `get_signals` pagination precedence, URL canonicalization on brand.json agent URLs, v3 envelope integrity schema constraint, format asset codegen titles, inline-enum hoisting
• Experimental surfaces — governance `mode` field, TMP `seller_agent` field. Cross-links to the experimental-status contract so adopters know why patch-level additions are permitted on those surfaces.
• Conformance harness — `force_task_completion` and `seed_creative_format` scenarios (sandbox-only)
• One docs-level deprecation — `get_signals` top-level `max_results` (still works in 3.x; removed in 4.0)

CHANGELOG.md framing (separate concern)

CHANGELOG.md follows the 3.0.0 convention — auto-generated `### Patch Changes` per-PR detail under `## 3.0.1`, with the curated narrative living in release-notes.mdx. The Version Packages PR's CHANGELOG.md content can stay as-is, OR a one-line lead-in can be added before merging:

```

3.0.1

See release notes for the curated narrative.
```

Test plan

• release-notes.mdx renders in Mintlify (no broken cross-references — all anchors resolve to existing pages: `/docs/reference/experimental-status`, `/docs/reference/url-canonicalization`, `/docs/reference/migration`)
• Pre-commit hooks pass
• CI green on PR
• Land before merging Version Packages PR (Version Packages #3042)

🤖 Generated with Claude Code