[Feature] Simplify Track Editor and main UI widget entry points

[chdenat]

Context

The Track Editor drawer currently exposes Profile and Journey Statistics widget
surfaces. The main UI also provides a button that adds a Text widget. These
entry points do not belong in the intended simplified editing workflow.

Requested behavior

Remove Profile and Journey Statistics widget displays and entry actions from
the Track Editor drawer.

Remove the main UI button that adds a Text widget.

Acceptance criteria

• The Track Editor drawer no longer displays Profile widget content or actions.
• The Track Editor drawer no longer displays Journey Statistics widget content
  or actions.
• The main UI no longer exposes the Text widget add button.
• Removing these entry points does not delete existing Profile, Statistics, or
  Text widget configurations.
• Existing persisted widgets remain recoverable through their supported
  remaining management surfaces.
• Replay, video-board composition, Draft capture, and HQ export remain
  functional.
• Focused UI regression tests cover the removed controls and retained widget
  behavior.

Technical notes

Audit TracksEditor, JourneySettings, WidgetManager, ElevationProfile,
Profile and Statistics widget entry points, and TextButton in MainUI.
Keep widget definitions and persistence intact unless a later approved issue
explicitly removes the widgets themselves.

[chdenat]

Implemented and pushed in commit 96afa6f (feat(ui): simplify widget entry points). Focused UI validation passes: 3 files, 9 tests.