Documentation & community: contributor tooling and docs

[don-petry]

Summary

The README is solid for a 4-day-old project, but several standard documentation and community scaffolding pieces are missing.

Items

1. No CHANGELOG.md

No structured release history. --generate-notes on GitHub Releases produces a raw commit list, but users browsing the repo have no way to see what changed between versions. Consider git-cliff or release-please for automated changelog generation.

2. No CONTRIBUTING.md

AGENTS.md is excellent for AI coding agents but there is no human-oriented contributing guide covering: development setup, how to run tests, PR workflow expectations, coding standards, or how to report bugs.

3. No issue templates

.github/ISSUE_TEMPLATE/ does not exist. Structured templates for bug reports (expected behavior, actual behavior, reproduction steps, environment) and feature requests would improve issue quality.

4. No PR template

.github/PULL_REQUEST_TEMPLATE.md does not exist. A checklist (tests pass, clippy clean, docs updated, etc.) helps contributors and reviewers.

5. No man pages

clap_mangen can generate man pages from the existing clap definitions. These could be included in release archives and installed alongside the binary.

6. Minimal --help text

CLI help text is auto-generated from struct doc comments but has no usage examples. Adding #[command(after_help = "EXAMPLES:\n ...")] to key commands would help new users.

7. No architecture documentation

AGENTS.md has design principles but no module-level docs explaining the overall architecture (how CLI/core/store/ui layers interact, the plan/apply pattern, the sync pipeline phases). A brief ARCHITECTURE.md would help new contributors orient quickly.

8. No Homebrew tap

Installation is limited to downloading binaries from GitHub Releases or building from source. A Homebrew tap would significantly lower the barrier on macOS. Could be automated in the release workflow.

9. Missing Cargo.toml metadata

The following fields are missing and would improve discoverability: description, repository, homepage, readme, keywords, categories, authors, rust-version.

10. crates.io name conflict

The dagger crate name on crates.io is taken by a different project. May need to publish as dgr or dagger-cli if crates.io distribution is desired.