Release v0.2.0

Headline: liam is no longer read-only — `liam create` adds a write
surface for posting Jira issues (Task / Bug / Story / …) with full
flag set, ADF descriptions, and a no-network `--dry-run` preview mode.

Also rolls up the work from MR !8 that landed all four open GitLab
issues at once:
- #12 — `liam create` write surface
- #10 — search tolerates Jira responses without top-level `total`
- #9  — `liam get` enriched with issuetype / resolution / comments
        + `--with-comments` and `--fields` flags
- #8  — README mise pin bumped to v0.1.8

Backfilled CHANGELOG entries for v0.1.5 / v0.1.6 / v0.1.7 / v0.1.8
which were tagged but never written.

Full notes: CHANGELOG.md