fix: pin Linux packaging sources to LF so AUR digests match on Windows

[roethlar]

Problem

Test · Windows has failed on every completed CI run on main since f5cf464 (2026-08-08). Two tests fail, both in tests/test_package_managers.py:

• AurGeneratorTests.test_pkgbuild_and_srcinfo_match_goldens
• AurGeneratorTests.test_generate_aur_package_writes_tree

The AppImage and installer builds were not affected.

Cause

The AUR generator hashes packaging/linux/am-configurator.desktop and am_configurator/data/60-am-neon-80.rules as working-tree bytes. The repo had no .gitattributes, so the Windows runner checked those files out with CRLF and the digests in the rendered PKGBUILD no longer matched the goldens.

Change

• Add .gitattributes pinning *.desktop, *.rules, *.sh, and packaging/linux/AppRun to LF.
• Drop the assertion in tests/test_packaging.py that .gitattributes must not exist. It was listed as a removed path only because its single rule was the FFmpeg manifest rule. The guard that fails when the retired token appears in .gitattributes is unchanged.
• Record the repair in .agents/state.md.

Verification

• Reproduced in a core.autocrlf=true clone of 4cf4d13: the same 2 tests fail with the same digests as CI. With .gitattributes added, all 21 tests in the module pass.
• Token guard still bites: reintroducing the retired token into .gitattributes fails test_current_surfaces_have_no_retired_media_tool_reference.
• Full local entry point on macOS: 769 Python tests, 193 web tests, compileall, all node --check steps, and uv build pass.
• The Windows runner result is this PR's CI run.

🤖 Generated with Claude Code