bug(commands): duplicate and conflicting command registrations

[akougkas]

Problem

Duplicates (same handler, different name):

• /status → alias for /dashboard (both call showDashboard)
• /thinking → alias for /reasoning (both call handleReasoningCommand)
• /settings → alias for /preferences (both call handlePreferencesCommand)

Pi name conflicts (PanCode registers same name as hidden Pi built-in):

• /settings conflicts with Pi TUI SettingsSelectorComponent
• /session conflicts with Pi session info
• /hotkeys conflicts with Pi keyboard shortcuts display

These conflicts only work because shell-overrides.ts hides Pi's built-ins first. If overrides fail or are removed, PanCode's registrations will be silently skipped by Pi's reserved name check.

Marked for removal but still registered (locked decision #7):

• /preferences
• /thinking
• /dispatch-insights
• /status

Audit Reference

AUDIT-ISSUES.md: C2, C3, C4

Objective

Remove duplicates and resolve naming conflicts.

Deliverables

• Remove /status registration (use /dashboard only)
• Remove /thinking registration (use /reasoning only)
• Remove /dispatch-insights registration
• Remove /preferences registration (use /settings only)
• Rename PanCode's /settings to avoid Pi conflict (or document the dependency on shell-overrides)
• Rename PanCode's /session if shell-overrides removal is planned
• Update /help to reflect removed commands