feat(tui): wrap-around arrow navigation for list pickers

[shayne-snap]

What changed

All list-type pickers in the TUI now support wrap-around arrow-key navigation: pressing ↑ on the first item jumps to the last item, and pressing ↓ on the last item jumps back to the first.

Affected lists:

• Slash-command option lists (/model, /permissions, /stats, ...), @ file suggestions, $ skill suggestions
• Permissions menu, /model picker (model/effort/thinking stages), request_user_input option modal, plan-implementation confirm
• /review menu and branch/commit/PR target picker, help panel
• Workflow launch confirm, workflow panel runs/phases/tasks/detail sections
• Plugins / config / skills managers, hooks manager (events + handlers), session picker

A shared wrapSelection(selected, count, delta) helper handles the cycling safely for empty lists. Approval modal and worktree-exit already wrapped and are unchanged; input-history navigation is intentionally left as-is (it is history, not a list picker).

Why

Arrow keys previously clamped at the boundaries, so moving up from the first item did nothing instead of cycling to the end. Wrap-around is the standard list UX (fzf/vim-style) and makes long lists faster to navigate in both directions.

What I tested

• gofmt clean, go build ./internal/tui/ ok
• New unit tests for wrapSelection plus behavior tests covering slash/skill/file suggestions, permissions menu, help panel, workflow launch, and session picker wrap-around
• go test ./... passes locally (full suite)

[shayne-snap]

Reopening to trigger CI — no workflow run was created on open