fix(lazy-deps): detect active features by primary package

[tianma-if]

Summary

• treat a lazy feature as active only when its first, backend-identifying package is installed
• prevent shared transitive pins such as aiohttp from marking Slack, Matrix, Discord, or Teams active
• update active feature regression coverage for the primary-package contract

Fixes #58458.

Tests

• .venv/bin/python -m pytest tests/tools/test_lazy_deps.py -q
• .venv/bin/python -m ruff check tools/lazy_deps.py tests/tools/test_lazy_deps.py

[alt-glitch]

This was generated by AI during triage.

Duplicate of #54178 — same code site (active_features in tools/lazy_deps.py) and same mechanism: gate activation on the primary/signature package rather than any declared spec, so a shared transitive pin (e.g. aiohttp) no longer false-activates never-enabled backends. #54178 is the earliest open canonical fix; the closed #58488 was the same fix. Relates to issue #58458.

[teknium1]

Thanks for the focused regression fix. The premise remains live on current main: tools/lazy_deps.py:870 still activates a feature when any declared spec is present, while platform.matrix retains secondary aiohttp==3.14.1 at tools/lazy_deps.py:175-184. The proposed primary-package condition prevents that shared pin from falsely activating Matrix and the other covered backends.

The change is isolated to the update-refresh detection heuristic and its regression coverage. The related marker-package implementation in ac4a9c681bd7fc85d2b1f211ad7a8caf42d2ddbf is not on current main; it does not supersede this PR.

Automated hermes-sweeper review.

[teknium1]

Fixed on main by #72361 — primary/anchor-package activation, same approach as this PR. #27878 by @paralegalia was the earliest submission (May 18) so it got the salvage credit. Thanks @tianma-if.