feat(agent/agentcontextconfig): discover skills from ~/.coder/skills by mafredri · Pull Request #25271 · coder/coder

The default skills lookup only scanned the project-relative
.agents/skills directory, so personal skills had to be repeated
per project or wired in via CODER_AGENT_EXP_SKILLS_DIRS. Now the
default is the comma-separated list ~/.coder/skills,.agents/skills,
which lets discoverSkills's existing first-occurrence-wins policy
prefer home-scoped skills over project ones with the same name.

The change is additive when ~/.coder/skills is absent
(missing directories are silently skipped in discoverSkills) and
unaffects users who set the env var explicitly.

Closes CODAGT-403.