build(aur): add PKGBUILD for installing taskdog via pacman/yay

[Kohei-Wada]

What

Adds contrib/aur/ with a PKGBUILD so taskdog can be installed on Arch Linux via pacman/yay, as an alternative to make install (which uses uv tool install into ~/.local).

Putting this up for review — not necessarily for merge. It's the venv-bundled approach; merging means committing to maintain it.

Approach (venv-bundled, -venv suffix)

Surveyed how comparable Python apps ship on the AUR. Two routes exist:

• Native (depends=('python-*')): idiomatic but several deps (python-uvicorn + uvicorn[standard] extras) aren't in the official repos/AUR, so you'd have to package and maintain them too.
• venv-bundled (this PR): vendors deps into a venv. Non-idiomatic but self-contained and low-maintenance. This is what aider-chat-venv and paperless-ngx-venv do.

Followed the AUR convention: package name taskdog-venv with provides/conflicts=('taskdog'), reserving the plain taskdog name for a possible future native package.

What the PKGBUILD does

• Builds a relocatable virtualenv on the system Python (uv venv --relocatable), installs taskdog's 5 packages from the release tarball (non-editable), third-party deps from PyPI.
• Ships the venv under /usr/lib/taskdog, symlinks taskdog / taskdog-server / taskdog-mcp into /usr/bin.
• Installs the systemd user service to /usr/lib/systemd/user/.
• UV_NO_INSTALLER_METADATA=1 (no direct_url.json / no $srcdir refs) + compileall --invalidation-mode unchecked-hash so the read-only /usr install never recompiles at runtime.

Verified locally

• makepkg builds cleanly; pacman -U installs; pacman -Q taskdog-venv registered.
• All three binaries run; taskdog table reads the existing per-user DB end-to-end.
• Startup parity with the uv tool install (--version ~0.25s) thanks to shipped bytecode — without it, the read-only /usr venv recompiled every run (~1.3s).
• Per-user data in $XDG_DATA_HOME/taskdog/ is never touched by the package.

Caveats (documented in contrib/aur/README.md)

• arch=('x86_64') (bundled wheels like pydantic-core are platform-specific).
• venv is built against the system Python → a major Python upgrade needs a rebuild.
• Build pulls deps from PyPI at build time (outside makepkg's source control) — fine for personal/AUR use, not official-repo quality.
• Not published to the AUR yet; that's a separate manual step (needs an AUR account + SSH key).

Build artifacts (src/, pkg/, *.tar.gz, *.pkg.tar.zst) are gitignored.

🤖 Generated with Claude Code

[amazon-q-developer]

The PKGBUILD implementation follows Arch Linux packaging conventions correctly. The venv-bundled approach is well-documented with appropriate caveats. The build and package functions properly handle virtualenv creation, bytecode precompilation, and systemd service installation. The .gitignore appropriately excludes build artifacts. No blocking defects found.

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