Add open-source project scaffolding: contributor docs, issue/PR templates, and lint CI

[Kantosaurus]

Summary

Dusky ships MIT + README + .gitignore and nothing else in the way of project infrastructure. This PR adds the standard open-source scaffolding a project of this size benefits from — contributor docs, issue/PR templates, CI, and line-ending enforcement — plus a small script bugfix found along the way. No behavioural changes to the desktop; this is repository health only.

What this adds

Community health (.github/)

• CONTRIBUTING.md — development setup for the bare-repo deployment model (how to edit safely without scattering files into $HOME), shell and Python conventions matched to the existing tree, and how to add a setup subscript.
• CODE_OF_CONDUCT.md — Contributor Covenant 2.1.
• SECURITY.md — a vulnerability-reporting policy, plus the things a user should understand before installing (privileged install scripts, networking helpers, the wireless tooling).
• SUPPORT.md — routes questions to Discord and the included docs.

Issue / PR flow

• Structured bug-report and feature-request forms that capture the fields most issues hinge on: GPU vendor, filesystem, install method, machine type.
• A PR template with a "tested on" section, and an issue-template chooser linking to Discord, the video walkthrough, and the in-repo Obsidian docs.
• A Dependabot config for the GitHub Actions used by CI.

CI + consistency

• lint.yml — checks shell syntax (bash -n), Python syntax (py_compile), and CRLF line endings on every push and pull request.
• .gitattributes — pins all text files to LF. This is load-bearing: Dusky deploys with git checkout -f into $HOME, and a script that lands with CRLF fails at exec time on Arch with /usr/bin/env: 'bash\r': No such file or directory. Two tracked text files that had CRLF endings are renormalized (the large line counts in those two files are line-ending-only changes).
• .editorconfig — matches the existing 4-space convention.

Docs

• README restructured with a table of contents, badges, clearer install steps, a grouped feature overview, and a contributing section — all existing content preserved. A few stale script paths and the keybind for the cheatsheet are corrected to match the actual scripts.
• CHANGELOG.md seeded from the recent history.

Bugfix

• dusky_tui_4.3.0.sh had a conditional block closed with } instead of fi, so the script failed to parse and could not run. Corrected.

Verification

The lint workflow passes on this branch: bash -n is clean across all shell scripts (the dusky_tui fix is what makes it 0 failures), py_compile is clean across all Python, no tracked file has CRLF, and all added YAML validates.

Notes

SECURITY.md here is the standard "how to report a vulnerability" policy; it is generic and does not describe any specific issue.

[dusklinux]

What model was used for all this?

[Kantosaurus]

Claude opus 5.0