[FEATURE] Support slash command autocomplete for all /commands on a line, not just the first

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When chaining multiple slash commands on a single prompt line (e.g. /commit /simplify), autocomplete only activates for the first command. After Tab-completing the first skill, typing a second / produces no dropdown — the user must type the full command name from memory with no discovery or completion support.

This creates a UX inconsistency: the first skill feels first-class, but every subsequent skill on the same line is invisible to the autocomplete system. The gap is most noticeable precisely when autocomplete would be most useful — when the user is already in a multi-command flow and wants to chain operations quickly.

Proposed Solution

The autocomplete system should recognize any / that appears at a word boundary (preceded by whitespace or at start-of-line) as a potential slash command trigger — not just the first / on a line.

Ideal behavior:

• Typing /commit then /sim surfaces matching skills (e.g. /simplify) in the dropdown
• Tab completes the second command just as it does the first
• The autocomplete anchor follows the cursor position rather than being fixed to column 0

To avoid false positives, / inside URLs (https://...) or filesystem paths (/usr/local/...) should not trigger command autocomplete — a "preceded by whitespace or start-of-line" heuristic covers this.

Alternative Solutions

Currently, users must invoke commands one at a time in separate prompts, or memorize exact skill names to chain them. There is no workaround that preserves the autocomplete experience for secondary commands.

Priority

Low

Feature Category

Interactive mode (TUI)

Use Case Example

1. I want to commit my current changes and then run a code simplification pass
2. I type /commit — autocomplete triggers, I Tab to complete it
3. I type a space and then / to start a second command
4. Current behavior: no dropdown appears; I must type /simplify in full
5. Desired behavior: the dropdown appears, filtered by what I've typed after /, and Tab completes it

Additional Context

The fix likely involves generalizing the autocomplete trigger from "position 0" or "first / match" to "any / preceded by whitespace or start-of-line." The dropdown positioning logic may also need to anchor relative to cursor position rather than a fixed column offset.