[FEATURE]: Add hints toggle to declutter UI

[tuanhqv123]

Problem

The TUI UI displays several persistent hints that can feel cluttered:

• /share copy link text in header
• [Tab] switch agent hint in prompt footer
• [Ctrl+P] commands hint in prompt footer

These hints take up screen real estate and become redundant once users are familiar with keyboard shortcuts.

Proposed Solution

Add a single toggle command "Hide hints" (KV key: hints_visible, default: true) that hides all UI hints:

1. Header: Hide /share copy link (but keep URL display when already shared)
2. Prompt footer: Hide [switch agent] and [commands] hints

Layout Behavior

Show hints = true (default) - Current layout:

Header:
  # Session Title           1,234 tokens (12%)
  /share copy link

Prompt:
  [Agent Name | Model | Provider]
  [Spinner|Esc] ........................ [Tab] switch agent  [Ctrl+P] commands

Show hints = false - Compact layout:

Header:
  # Session Title           1,234 tokens (12%)

Prompt:
  [Agent Name | Model | Provider] ... [Spinner|Esc]

Note: When hints are hidden, the spinner and esc interrupt move to the right side of the same row as the agent/model/provider info.

Implementation Details

• Added hints_visible KV setting (default: true)
• Added command session.toggle.hints in command palette
• Modified Header.tsx, Prompt.tsx, and session/index.tsx
• Replaced 3 separate toggle signals with single showHints signal
• Preserved existing behavior for spinner/interrupt display during active operations

Alternatives Considered

1. Separate toggles for each hint - rejected: too granular, increases config surface
2. Per-hint keybind toggles - rejected: would require more keybinds, harder to discover
3. Auto-hide after X sessions - rejected: doesn't allow user control

Questions for Maintainers

• Is this something that aligns with OpenCode's design philosophy?
• Should we also hide other hints (like /status, LSP/MCP counts) in footer?
• Any naming preferences for the command/setting?

Code

I have implemented this change. Branch: feature/hints-toggle
Fork: https://github.com/tuanhqv123/opencode/tree/feature/hints-toggle

Waiting for design review approval before opening PR.

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• [FEATURE]: focus mode to toggle off all the decorations #4786: [FEATURE]: focus mode to toggle off all the decorations (very similar - proposes hiding all decorations to reduce UI clutter)
• [FEATURE]: Subagent sessions accumulate without cleanup option - causes storage bloat and UI clutter #5734: [FEATURE]: Subagent sessions accumulate without cleanup option (related - addresses UI clutter from accumulated sessions)

Feel free to ignore if none of these address your specific case.