docs: document all CLI slash commands in TUI mode

[fahe1em1]

Description

Closes #11316.

This updates the TUI slash command table so it matches the commands currently exposed by the CLI. It adds the missing slash commands, refreshes a few outdated descriptions, and notes that /diff and /apply are only available in remote environments. The change is intentionally small and safe because it only updates user-facing documentation in a single file and does not affect runtime behavior.

Checklist

• The relevant docs, if any, have been updated or created
• The relevant tests, if any, have been updated or created

Tests

• npx --yes prettier --check docs/cli/tui-mode.mdx

Why this is small and safe

• This PR only changes documentation for existing commands.
• No code paths, configs, or shipped behavior are modified.

---

Summary by cubic

Update TUI mode docs to list all current CLI slash commands and refresh outdated descriptions so the table matches the CLI. Also note that /diff and /apply are only available in remote environments.

^{Written for commit a7eb2dd. Summary will update on new commits.}

[github-actions]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[cubic-dev-ai]

No issues found across 1 file

---

Since this is your first cubic review, here's how it works:

• cubic automatically reviews your code and comments on bugs and improvements
• Teach cubic by replying to its comments. cubic learns from your replies and gets better over time
• Add one-off context when rerunning by tagging @cubic-dev-ai with guidance or docs links (including llms.txt)
• Ask questions if you need clarification on any suggestion

[fahe1em1]

recheck