Add configurable platform acronyms & icons for unpacking

[luandev]

Add configurable platform acronyms & icons for unpacking

Problem
Platform acronyms and icons are hardcoded, preventing custom folder names and visuals during unpack/organization.

Goal
Let users override acronyms and icons per platform, applied across unpack, scan, and UI.

Scope

• Data:

  • settings.platformAcronyms: { [platformId]: acronym }
  • settings.platformIcons: { [platformId]: iconSlug }
  • Defaults from @crocdesk/shared

• API:

  • Extend GET/PUT /settings to include overrides
  • Validate: acronym [a-z0-9-_]{2,12}, icon must exist

• Behavior:

  • Unpack path: {acronym}/{gameTitle}/…
  • Manifest includes platformAcronym
  • Fallback to defaults when unset

• UI:

  • Settings section with acronym input + icon picker
  • Live folder preview, validation, reset to defaults

• Migration:

  • Backfill new settings keys with defaults

• Testing:

  • Unit: precedence, validation, fallback
  • E2E: unpack/scan use overrides; UI persists

Acceptance

• Per-platform overrides configurable and persisted
• Unpack/scan consistently use overrides
• Manifests stay backward compatible
• UI reflects overridden icons and acronyms