chore: remove 15 unused imports (fixes #984)

[chrisyangxiaoqi]

Summary

Removes all imports in src/backend/routers/agents.py that trigger ruff F401 errors (imported but unused).

Changes

The following imports were removed:/n- docker (line 14)

• pathlib.Path (line 16)
• services.docker_service.docker_client (line 25)
• services.docker_utils.container_reload (line 30)
• services.docker_utils.volume_get (line 31)
• services.docker_utils.volume_remove (line 31)
• services.image_generation_prompts.AVATAR_EMOTIONS (line 34)
• services.git_service (line 33)
• services.agent_service.get_agents_by_prefix (line 44)
• services.agent_service.get_next_version_name (line 45)
• services.agent_service.get_latest_version (line 46)
• services.agent_service.check_shared_folder_mounts_match (line 47)
• services.agent_service.check_api_key_env_matches (line 48)
• services.agent_service.recreate_container_with_updated_config (line 52)

Verification

ruff check src/backend/routers/agents.py --output-format=concise

No F401 errors remain.

Fixes #984

[vybe]

Thanks for the cleanup! 🙏 One process note before this can be merged:

Per Trinity's SDLC (CLAUDE.md → SDLC, and .claude/DEVELOPMENT_WORKFLOW.md), contributor PRs land on dev first — work flows feature → dev → main, and main only ever receives release PRs cut from dev. This PR is currently based on main.

Could you retarget the base branch from main to dev? You can do it in place: click Edit next to the PR title and change the base dropdown to dev — no need to close/reopen. (You may need to rebase onto dev afterward.)

Thanks again for the contribution!

[vybe]

Heads up @chrisyangxiaoqi — this PR targets main, but Trinity's flow is feature/* → dev → main (only release cuts and hotfix cherry-picks go straight to main). Could you retarget the base branch to dev? The change itself (removing 15 unused imports, fixes #984) is fine — just needs to land on dev so it flows through the normal integration → release path. You can switch the base via the 'Edit' button at the top of the PR.