docs: Add versioned docs for v0.6 (#725)

- Add versioned docs for Client v0.6 docs (last zero-based version)
- Fix `SUCEEDED` → `SUCCEEDED` typo in v0.6 API typedoc
- Add `**/changelog.md` exclusion to `typos.toml`
- Remove inner `.gitignore` files from versioned docs dirs, use
top-level `.gitignore` instead

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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>