ci: align triggers + route dependabot through develop

[BrainInBlack]

What & why

Aligns the CI triggers with home-brew-tap and setup for develop > main workflow.

Type of change

• Bug fix
• New feature / option
• Documentation only
• Refactor / cleanup (no behavior change)

Checklist

• One focused change, with a short description of the why (above).
• Stays portable: runs on stock macOS bash 3.2 — no mapfile/readarray, associative arrays, ${var,,}, or other bash 4+ features.
• Stays single-file with no new runtime dependencies beyond ssh/scp (and optional fzf).
• Linted locally — both pass clean:

  bash -n ssh-deploy
  shellcheck ssh-deploy

• Tests pass (bats test), and new behavior is covered by a test.
• Added a note under ## [Unreleased] in CHANGELOG.md.
• If behavior or flags changed, updated README.md and the in-script --help together.

Testing

NA