docs: note v0.3.2 as first immutable release (#68)

Immutable Releases is enabled at the repository level, but GitHub applies
it only to releases published after the setting was flipped. Publish
v0.3.2 as the first immutable tag and document in the README/CHANGELOG
so users know which tag to pin for supply-chain hardening.

Also bump example snippets from @v0.3.0 to @v0.3.2 and backfill the
skipped v0.3.1 changelog entry.

Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>

Only show use-pro deprecation message on top action input (#67)

Use the LocalStack pro image by default (#63)

update actions and use hashes instead of version tag (#60)

Add support for LOCALSTACK_AUTH_TOKEN on ephemeral instances suite (#47)

Fix action version in readme (#40)

Support preview stage of ephemeral instances

Fix download actions (#30)

Refactor code (#17)

DOCS: Add relevant documentation for new input variables