fix: home channel auto-prompt now checks yaml config

[nightq]

Summary

Fixes the home channel auto-prompt to check yaml config in addition to env var.

Root Cause

The one-time home channel prompt only checked the env var (os.getenv(f"{PLATFORM}_HOME_CHANNEL")) but never consulted the yaml-persisted config that /sethome writes. This caused the prompt to re-fire for fresh sessions even after a user had already run /sethome.

Fix

Check both env var and config.get_home_channel() before showing the prompt. The prompt now only appears if neither source has a home channel set.

Changes

• Modified home channel check in gateway/run.py to check both env var and yaml config before showing the one-time prompt

Test Plan

• All home channel related tests pass (8 tests)
• Manual verification of the fix logic

Closes #10581

[alt-glitch]

Related to #10632 and #12391 — all three PRs fix the same root cause (home channel check only reads env var, misses yaml config from /sethome). See also parent issue #10581.

[teknium1]

Thanks for tracing the home-channel prompt path. This is now redundant because current main fixed the underlying persistence path rather than adding a YAML fallback.

• Automated hermes-sweeper review verified commit 1d5e25f35367af7ff15856bca232ba44bd0bc84f (fix(gateway): persist /sethome home channel to .env across all platforms), which replaced the former top-level config.yaml write with save_env_value().
• Current /sethome uses that path at gateway/slash_commands.py:2430-2452; save_env_value() writes .env and updates os.environ at hermes_cli/config.py:7581-7603.
• The onboarding check at gateway/run.py:11397-11418 reads the same platform home-target environment key, so a home channel set by /sethome suppresses the notice without the proposed YAML lookup.
• This also addresses the parent-report persistence failure discussed in [Bug]: Home-channel auto-prompt only checks env var, never falls back to yaml config #10581 and the related PRs noted in the discussion.

Closing as implemented on main.