Release v0.2.0 — guided-push UX polish (#44, #47) + CI matrix guard (#46)

[saadqbal]

Context

Next release after v0.1.0. Since v0.1.0, develop gained two user-facing feats — friendlier guided dataset push (#44) and dataset rm on the home screen + in-run guidance (#47) — plus the build.yml all-arch CI guard (#46). Two feat commits → minor bump per semver → v0.2.0.

Release infra (8-arch matrix, cosign signing, install scripts) is already in place from v0.1.0 — no workflow changes needed.

Scope

• README: Status line → v0.2.0; reconcile the Roadmap "Next (v0.2)" framing (cloud-sources etc. move to the next milestone, since v0.2.0 ships UX polish, not cloud ingestion).
• Pre-flight: develop green (✓), all 8 targets cross-compile, go test -race ./....
• Tag v0.2.0 off develop (no - → stable release).

Acceptance criteria

• README accurate for v0.2.0.
• v0.2.0 published: 8 signed binaries + SHA256SUMS + install scripts; releases/latest → v0.2.0.

[saadqbal]

Shipped: v0.2.0 is published as a stable release (27 assets — 8 signed platform binaries + SHA256SUMS + install scripts). First release run hit a transient cosign-installer download flake on the windows/amd64 job (curl exit 22 from GitHub's CDN); a re-run of the failed job succeeded and publish created the release. releases/latest → v0.2.0.