Add desktop sidecar for live queue visibility

[steve-the-edwards]

Summary

• add a minimal Compose Multiplatform desktop sidecar that reads the existing queue.db directly
• redesign the sidecar around a topology-first queue board plus a running-now strip so queue setup, active work, and FIFO waiting order are easier to scan
• show running-task origin metadata in the sidecar, including repo/worktree, git branch, caller label, and a visibly ticking running timer when that metadata is available
• document how to run the sidecar and ignore its local Gradle build outputs

Validation

• ./desktop-sidecar/gradlew compileKotlinDesktop desktopTest
• uv run pytest tests/test_queue.py tests/test_tq_cli.py
• cd desktop-sidecar && ./gradlew run --args="--help"
• uv run ruff check .
• uv run pytest -v

Review

• amp review --files .gitignore README.md desktop-sidecar/ "uncommitted changes for the new Compose desktop sidecar app and docs"
• Amp suggested considering a long-lived DB connection for polling, but did not surface a correctness bug in the current minimal implementation.

[steve-the-edwards]

@codex review

[chatgpt-codex-connector]

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[shyamu]

Neat!