Add setting to hide the Remote Control footer pill while keeping RC enabled

Problem

For users who enable Remote Control on every session ("remoteControlAtStartup": true in settings.json), the persistent "Remote Control active" footer pill is visual noise — the state it communicates never changes.

Today the only way to remove the pill is "disableRemoteControl": true, which kills the feature entirely. That's an all-or-nothing tradeoff for a UI affordance most always-on users don't need to see.

Proposal

Add a setting to hide the footer pill while leaving Remote Control functional. Something like:

{
  "remoteControlAtStartup": true,
  "hideRemoteControlPill": true
}

Or as a nested option under a ui / footer namespace if that fits the existing schema better.

Why this isn't just a cosmetic ask

• Footer real estate is scarce — other persistent indicators (update available, /goal overlay, etc.) compete for the same slot.
• Users who deliberately set remoteControlAtStartup: true have already opted in; the pill is reminding them of a state they configured.
• Vim-mode footer navigation already has to special-case the pill (see changelog: "Fixed footer navigation selecting an invisible Remote Control pill in config-driven mode"), suggesting the codebase already supports an invisible-pill state.

Acceptance

• hideRemoteControlPill: true removes the pill from the footer
• RC continues to function normally (session linkable from claude.ai/code, mobile push, etc.)
• Default remains false so behavior is unchanged for existing users

Thanks!