refactor(word-addin): composer controls - apply-mode menu, workflows under "+", icon-only model picker

WHY THIS MATTERS
Composer feedback, three parts: (1) the Review on/off switch read as a
setting, not a choice - the mode belongs in a menu that names both options
and their consequences; (2) the standalone workflow button crowded the
action row for a feature reached occasionally; (3) the model picker's full
model name dominated the row. The row now holds "+", the apply-mode
control, and two icons - everything fits one line even in a narrow pane.

HOW IT WORKS
- The apply-mode control is a plain icon+label trigger (no background, no
  chevron): Eye "Review" or Pen "Edit". It opens the shared Dropdown
  (same primitive as the model picker) titled "How should edits be
  applied?" with a described option per mode and a check on the active
  one:
    Review - Review and propose tracked changes which are applied after
    approval (default)
    Edit - Directly edit the document in tracked changes
  Only the UI naming changes: the stored preference stays
  mike_word_edit_apply_mode = approval | direct, so existing users keep
  their choice.
- The workflow entry moves into the "+" menu alongside Desktop Files and
  Web files, opening the same WorkflowModal; the dedicated Waypoints
  button is gone. Attaching from the Workflows tab is unchanged.
- The model picker collapses to a Settings2 icon; the selected model's
  name lives in its tooltip and the menu itself.

Spec updates follow the semantics: the "no switches" guard reverts to
asserting zero switches (the mode control is a menu button, not an
opt-out); the apply-mode specs drive the dropdown (data-selected +
trigger label) instead of aria-checked; the workflow-attach spec opens
via "+ → Workflows"; and the narrow-pane spec asserts the single-line
action row in place of the removed button's geometry.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JN4mcnhSK7xpxzF2b3WFkE