Tab-completion for slash commands (skills) in the CLI prompt

Problem

When you have multiple skills with similar prefixes (e.g., /DOGGIE-1, /DOGGIE-2, /DOGGIE-3), there's no way to tab-complete them. You have to type the full command name or scroll through memory to find the exact one. This gets increasingly painful as the number of installed skills and plugins grows.

Proposed Behavior

• Typing /DOGG + [Tab] should show matching slash commands, similar to terminal autocomplete
• If there's a single match, auto-complete inline
• If there are multiple matches, show a dropdown/list of candidates (e.g., /DOGGIE-1, /DOGGIE-2, /DOGGIE-3)
• Should work for all registered skills, built-in commands, and plugin commands
• Namespaced commands especially benefit (e.g., typing /searchfit + Tab → shows all searchfit-seo:* skills)

Why It Matters

• Discoverability — users can explore available commands without memorizing exact names
• Speed — reduces typos and typing for long or namespaced command names
• Consistency — matches the UX expectation from every terminal, shell, and IDE
• Scales with the ecosystem — as plugins/skills grow, manual recall becomes untenable

Current Workaround

Type / and hope you remember the exact name, or use /help to list everything and manually scan. Neither scales well with 50+ skills installed.