Merge pull request #323 from puremachinery/refactor/shared-oauth-onboarding

fix: restore Gemini API-key hint in CLI error, gitignore docs/superpowers

Merge branch 'master' into refactor/shared-oauth-onboarding

fix: clean up test flow leaks, remove redundant callback_html wrappers, fix fmt

fix: remove dead _provider_config parameter from finish_oauth_flow

Merge pull request #329 from puremachinery/chore/dependency-pr-325-327

chore: process dependency PRs 325, 326, and 327

Merge pull request #324 from puremachinery/chore/release-v0.6.0

refactor: make plugin rename cleanup explicit

fix: avoid spurious plugin cleanup warnings

style: format plugin helper cleanup

refactor: tighten plugin atomic write helper

fix: harden plugin temp writes for release notes

docs: fix v0.6.0 release note examples

chore: prepare v0.6.0 release