Create 3 bundled SKILL.md files

[bug-ops]

Description

Write SKILL.md files for the initial set of built-in skills.

Parent: #3

Branch

feat/m2/bundled-skills

Files to Create

• skills/web-search/SKILL.md — DuckDuckGo search via curl + jq
• skills/file-ops/SKILL.md — File operations: ls, find, grep, cat, wc
• skills/system-info/SKILL.md — System info: uname, df, ps, uptime

Acceptance Criteria

• Each file has valid YAML frontmatter (name, description)
• Each has practical CLI instructions
• All parseable by skill loader
• Instructions tested manually (commands work on macOS/Linux)

Depends On

#12 (Skill loader)