[TAG-03] Add native mobile tag actions and management #13

ID: TAG-03 (TAG-001). Priority: P1. Blocked by: #11. Backlog: #1.

Scope and acceptance criteria

• Native thread action menu/bottom sheet supports manual assign/remove, clear
  filters and inspection of all tags. Provide definition management including
  rename/archive/restore without requiring a desktop client.
• Reuse shared scoped tag state and commands; no independent mobile ownership
  model. Tag mutations and conflicts behave like web/desktop.
• Compact accessible chips/details distinguish manual/derived and stale state
  without overloading phone rows. Tablet layouts remain usable.
• Exact scoped filtering and result navigation preserve the target environment
  even for identical tag labels and thread IDs on different machines.
• Cache is visibly stale while offline; mutation failure remains explicit.
  Reconnect applies compact updates without reloading full histories.
• Cover iOS/Android semantic behavior, keyboard/screen-reader labels, conflicts,
  archive/restore, reconnect and same-label cross-environment selection.

Reuse, coverage and non-goals

Use upstream native thread menus/filter state and shared client runtime.
All provider types and supported environment modes. TAG-02 is a parallel UI
slice, not a hard dependency. No tag-driven routing, derived assignment
inference, standalone worktree tags or mobile push changes.

Integrated simulator/emulator/browser use requires permission.