[Feature]: Show skills in slash command autocomplete menu

Before submitting

• I searched existing issues and did not find the same request.

Problem or unmet use case

Description

When typing / in the Claudian input box, the autocomplete dropdown only shows 4 built-in commands:

• /add-dir
• /clear
• /instruction
• /resume

No skills appear at all — not project-level (.claude/skills/), not user-level (~/.cache/opencode/skills/), not from any path.

The skills ARE loaded and functional — typing /skillname manually works — but users have no way to discover them from the UI.

Expected Behavior

Typing / should list all available skills alongside built-in commands, so users can discover and invoke them without memorizing names.

Actual Behavior

Only 4 hardcoded commands appear. All skills (I have 34 project-level ones) are invisible.

Steps to Reproduce

1. Place skills in .claude/skills/ (34 skills with valid SKILL.md files)
2. Open Claudian with OpenCode backend
3. Type / in the input box
4. Observe: only add-dir, clear, instruction, resume appear

Environment

• Claudian: v2.1.4
• Backend: OpenCode
• OS: Windows 11
• Skills location: .claude/skills/ (project-level)

Suggestion

Scan skill directories (.claude/skills/, .opencode/skills/, ~/.cache/opencode/skills/) on initialization and merge discovered skills into the slash command suggestion list.

Desired outcome

Expected Behavior

Typing / should display all available skills in the autocomplete dropdown alongside built-in commands. For example:

Affected provider

OpenCode

Proposed solution

No response

Alternatives considered

No response

Additional context

No response