Add wait-for-builds polling for Launchpad build completion

[rtibblesbot]

Summary

Adds a wait-for-builds subcommand to scripts/launchpad_copy.py that polls Launchpad until all builds for a source package reach a terminal state. This prevents the race condition where copy-to-series or promote operations proceed before Launchpad has finished building binaries.

The command operates in two phases:

1. Source appearance: Polls getPublishedSources until the expected package+version appears in the PPA (filtering out Deleted/Superseded/Obsolete sources)
2. Build completion: Polls getBuilds() on all matching sources until every build reaches a terminal state

CLI parameters: --package, --version, --ppa (default: kolibri-proposed), --timeout (default: 1800s), --interval (default: 60s). Exits 0 if all builds succeed, 1 on any failure or timeout.

Two new workflow jobs are inserted into the build_debian.yml release workflow:

• wait_for_source_builds: after build_package, before copy_to_other_distributions
• wait_for_copy_builds: after copy_to_other_distributions, before block_release_step/promote

References

Closes #107

Reviewer guidance

• The core polling logic is in LaunchpadWrapper.wait_for_builds() and _poll_builds() — review these for correctness of the state machine (terminal states, failure detection, timeout handling)
• The workflow changes add two new jobs with LP credentials handling — verify the needs dependency chain is correct
• Tests mock time.time and time.sleep to avoid real delays; the side_effect sequences simulate time progression
• The 4 skipped tests require ubuntu-distro-info which isn't available outside Ubuntu — this is expected

Test evidence

Test scenarios covered (48 passed, 4 skipped)

CLI argument parsing (13 tests):

• wait-for-builds subcommand recognized with required --package and --version
• Defaults: --ppa=kolibri-proposed, --timeout=1800, --interval=60
• Custom values for all parameters accepted
• Missing required args produce SystemExit

Build polling (14 tests):

• Source appears immediately → builds checked → success
• Source appears after retry (sleep called)
• Timeout when source never appears → exit 1 with error message
• Deleted/Superseded sources filtered out (treated as not-found)
• All builds succeed across multiple architectures → exit 0
• Checks ALL build records, not just first (amd64 ok + arm64 fail → exit 1)
• Single build failure → exit 1 with arch, state, and web_link logged
• Builds complete after retry (Currently building → Successfully built)
• Build timeout (still building at deadline) → exit 1
• Multiple sources all checked (cross-series after copy)
• No builds yet → keeps waiting until they appear
• Progress logging: "Waiting for builds: 2/3 complete, 1 building..."
• Custom PPA name passed through to get_ppa()
• Obsolete series handled gracefully during promote

Subcommand dispatch (3 tests):

• main() dispatches wait-for-builds to cmd_wait_for_builds
• Existing copy-to-series and promote dispatch unchanged

$ python3 -m pytest tests/ -v
48 passed, 4 skipped in 0.24s

$ ruff check scripts/ tests/
All checks passed!

$ ruff format --check scripts/ tests/
5 files already formatted

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@rtibblesbot's comments are generated by an LLM, and should be evaluated accordingly

How was this generated?

• Ran pre-flight CI checks (lint, format, tests) and verified all pass
• Rebased onto the target branch and resolved any conflicts
• Reorganized commit history into clean, logical commits
• Audited the diff to ensure only issue-relevant files are changed
• Built PR body from the repository's PR template with evidence blocks

Closes #107

[rtibbles]

Tested locally - seems to work, but I had some difficulties with dependencies.

The pyproject.toml doesn't contain any python dependencies for either test or regular operations.

I had to install:

• launchpadlib
• keyring
  To run the scripts

and pytest to run the tests.

[rtibblesbot]

Thanks for the review! Added Python dependencies to pyproject.toml — launchpadlib and keyring as runtime dependencies, pytest and vcrpy as test dependencies.

Addressed 1/1 review items. 0 deferred.