ci(cli): add CI and crates.io publish pipeline for cougr-cli

[therealbibson]

Summary

• Adds .github/workflows/cli.yml: fmt/clippy(-D warnings)/test/build for cougr-cli, path-scoped to cougr-cli/** so it doesn't run on unrelated changes (mirrors core.yml's job shape, using a working-directory default like example_reusable.yml since cougr-cli isn't a workspace member yet).
• Adds .github/workflows/publish-cli.yml: package → publish-to-crates.io (with the same crates.io pre-check guard as publish-crate.yml to skip already-published versions) → GitHub Release, triggered on main pushes touching cougr-cli/** and on cougr-cli-v* tags (distinct tag prefix so CLI releases don't collide with cougr-core's v* tags).
• No changes to core.yml or publish-crate.yml — cougr-core's existing CI/publish behavior is untouched.

Note: cougr-cli itself doesn't exist yet (tracked by the other sub-issues of #238). These workflows are path-scoped to cougr-cli/** and simply won't trigger until that crate lands — same pattern as the per-example workflows before their example directories existed.

Test plan

• Once cougr-cli/ is added as a workspace member (per Epic: ship the cougr CLI (new / add / check / doctor) #238's other sub-issues), open a PR touching only cougr-cli/** and confirm CLI CI triggers while the full example matrix does not.
• Bump cougr-cli/Cargo.toml's version on main and confirm Publish CLI Crate publishes to crates.io and cuts a GitHub Release tagged cougr-cli-v<version>.
• Reviewed YAML structure against core.yml, publish-crate.yml, and example_reusable.yml for consistency.

Closes #248

[drips-wave]

@therealbibson Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[salazarsebas]

The workflow content itself (fmt/clippy -D warnings/test/build, crates.io version check, GitHub Release) looks correct and matches the pattern from core.yml/publish-crate.yml. One blocker before merge: this workflow is path-scoped to cougr-cli/** and uses working-directory: cougr-cli, but the crate is actually being created at cli/ in #288 (and in #277/#279/#280). We're consolidating on a single canonical location for the CLI crate — see the merge-order discussion on #275/#288 — please hold this PR until that's settled, then update the paths to match before merging.

[salazarsebas]

This is scoped to cougr-cli/** in the path filters, but the actual crate on main lives at cli/ — as written, this workflow would never trigger. Could you rebase onto main and update the paths to cli/**? Also worth double-checking the crate name in the publish step matches what's in cli/Cargo.toml.