Fixes#160
## Changes
Extracted phase callback functions (post_refusal_comment, do_merge, _on_phase_change) from dev/dev-agent.sh into new dev/phase-handler.sh. dev-agent.sh now sources both lib/agent-session.sh and dev/phase-handler.sh. Replaced inline dependency extraction with lib/parse-deps.sh. dev-agent.sh reduced from 1516 to 684 lines (55% reduction). AGENTS.md shellcheck command updated to include the new files.
Co-authored-by: openhands <openhands@all-hands.dev>
Reviewed-on: https://codeberg.org/johba/disinto/pulls/173
Reviewed-by: Disinto_bot <disinto_bot@noreply.codeberg.org>
