feat: add support for .claude/skills directory

[connorads]

As per docs, intention was to suppport .claude/skills
https://opencode.ai/docs/skills/

I can see .claude/skills support was removed in 009b096 by @rekram1-node. Seems like this might have been because of another issue #5991 (comment) which I think has since been fixed here by removing the regex 046e351#diff-54184cd5893ffa6ad25945157739a92970d03937b46c73ee9e3c3838de3c52fd

Fixes#6177

PS. I'm also happy for you to change this implementation to be more like 009b096, where it walks up from cwd to worktree, I didn't know that existed when I started working on this fix.

Testing

Before
No .claude/skills ❌

➜ opencode debug skill
[
{
"name": "global-opencode-skill",
"description": "Global .opencode skill for troubleshooting discovery.",
"location": "/Users/connorads/.config/opencode/skill/global-opencode-skill/SKILL.md"
},
{
"name": "test-skill",
"description": "use this when asked to test skill",
"location": "/Users/connorads/git/opencode/.opencode/skill/test-skill/SKILL.md"
}
]

After
claude/skills loaded ✅

➜ bun dev debug skill $ bun run --cwd packages/opencode --conditions=browser src/index.ts debug skill
[
{
"name": "global-opencode-skill",
"description": "Global .opencode skill for troubleshooting discovery.",
"location": "/Users/connorads/.config/opencode/skill/global-opencode-skill/SKILL.md"
},
{
"name": "test-skill",
"description": "use this when asked to test skill",
"location": "/Users/connorads/git/opencode/.opencode/skill/test-skill/SKILL.md"
},
{
"name": "local-claude-skill",
"description": "Local test skill for validating skill loading.",
"location": "/Users/connorads/git/opencode/.claude/skills/local-claude-skill/SKILL.md"
}
]

[rekram1-node]

This doesn't quite work actually

[connorads]

This doesn't quite work actually

Thanks for the feedback, could you elaborate please?

[rekram1-node]

This doesn't restore the functions that this commit removed (note the start & stop) for Filesystem.up:
009b096

Also we should read the global claude skills too

[rekram1-node]

ig the behavior was changed by someone else, so ig this "works"

[rekram1-node]

ignore my previous comment, I think there was an unintentional regression that this builds off of, not ur fault tho, merging