chore(release): bump project version to 0.3.0

[tcheeric]

Summary

Bump project version to 0.3.0 to reflect recent REST feature additions and fixes (POST create for Quote/Payment with entity body responses) since 0.2.2. Also updates the changelog for
0.3.0.

Related issue: #____

What changed?

• Parent and module POM versions updated to 0.3.0:
  • pom.xml and module POMs under cashu-gateway-*
• Changelog updated:
  • docs/reference/changelog.md: add 0.3.0 section
• Note: This branch currently includes nbactions.xml and cashu-gateway-phoenixd/logs/* added by local tooling. If undesired, I can remove them and update .gitignore.

BREAKING

None. This is a minor version bump aligned with new features and fixes; no API breaks intended.

Review focus

• Confirm all module POMs reference parent 0.3.0.
• Confirm jib tags still use ${project.version} where applicable.
• Confirm 0.3.0 changelog wording/placement.

Checklist

• Scope ≤ 300 lines (or split/stack)
• Title is verb + object
• Description links the issue and explains “why now?”
• BREAKING flagged if needed
• Tests/docs updated (changelog updated; no code changes)

Build and tests

• Command: mvn -q verify
• Result: Test failures in cashu-gateway-phoenixd due to sandboxed environment preventing Mockito Inline/Byte Buddy self-attach on JDK 21 (not a code regression).

  • Excerpt:

    Could not initialize inline Byte Buddy mock maker.
    It appears as if your JDK does not supply a working agent attachment mechanism.
    Caused by: IllegalStateException: Could not self-attach to current VM using external process

• Notes:
  • This typically passes in environments where the JVM allows agent attach. If CI is similarly restricted, consider:
    • Running with a non-inline mock maker for those tests, or
    • Temporarily skipping those tests in restricted environments, or
    • Running mvn -q -DskipTests=true verify for this release-only PR.