docs: mark Google Play as available, skip CI on docs-only changes

[pasichDev]

What and why

• Google Play is live. Encly is on Google Play. In the README, the coming-soon badge is replaced by a linked badge, and the channel is marked available in the install table. In CONTRIBUTING, the one-time Play step is marked done.
• No CI on docs-only changes. A docs-only change used to start a full Android CI run (~7 min), e.g. docs: mark F-Droid as available #50. android.yml now sets paths-ignore on both push and pull_request for **.md, docs/**, LICENSE and .github/ISSUE_TEMPLATE/**. fastlane/** still triggers CI, because StoreMetadataTest validates the store texts. A change that touches a doc and anything else runs CI in full. main has no required checks, so a skipped run does not block a merge.

How it was tested

• ./gradlew :app:testFdroidDebugUnitTest --tests '*CodeQualityToolingTest*' --tests '*StoreMetadataTest*' passes (CodeQualityToolingTest reads android.yml)
• No unit test reads Markdown or docs/. Tests read only fastlane/, version.properties and the workflows
• The Play listing and the badge URL both return 200
• This PR runs CI itself because it changes the workflow. The skip is first confirmed on the next docs-only PR

Security and data checklist

• No app code changes.

[github-actions]

Coverage (core/security)

Overall Project	68.54%	🍏

There is no coverage information present for the Files changed