Settings UX: show separate System Image, TrainerOS Software and game updates #155

Parent: #153. Depends on #154 and image OTA #71. Applies across handheld and TV layouts (#156).

Goal

Make update ownership understandable to ordinary users, without duplicating SteamOS/Bazzite Settings or showing a misleading OS update button on a host we don't own.

User-facing destinations

Under the existing Start → Settings → System → Updates (or a similarly compact native menu), show:

TrainerOS Software
Version S.12       New version S.13 available
[Update TrainerOS]     [What's new]

System Image                     (prepared image only)
Armada base I.3   New version I.4 available
[Update System]      [Details]

Installed Games
OddCrate  ·  3 updates            [View in OddCrate]

Host system (SteamOS/Bazzite installations)
Updated by your Linux distribution [Open host settings if available]

Do not present System Image installation controls when running as a TrainerOS session on SteamOS/Bazzite. That host's distro owns its own updates. Display status/link only when safe and supported, never act as an alternative host updater.

Behavior

• Separate state, version/release notes, download size, available space, install progress, restart requirement, failure/rollback for image and software.
• Distinguish Software update requires restart of TrainerOS from System update requires device reboot; do not claim all updates can be applied live.
• The client must not reboot merely to apply a validated policy-only software update if its actual loader can safely switch policy versions.
• A prepared image can have newer software without a newer image; UI should never call it 'outdated' solely because image version lags.
• If only policies changed, show a concise software security/content-policy update without unnecessarily displaying the underlying forbidden-title database.
• If offline, show last checked/current release and let installed games play.
• The game update entry links to OddCrate's normal installed-game management, not another updater implementation.

TV readability

TV mode uses large, legible status rows, correct safe-area margins and controller focus; update actions may require explicit confirmation, not one accidental A press on a remote.

Acceptance

• Prepared image user can inspect/install image and software independently.
• SteamOS/Bazzite user sees software update and understands host OS is external; no Flash system image control appears.
• OddCrate game updates are separate and stay accessible from the relevant games.
• Policy-only release presents as TrainerOS Software, not as host/system image.
• Mid-game and pending-save update states clearly defer safely.
• No conflicting update progress/state after switch between handheld and TV mode.