Core Filtering: Filter Tree by Page Names

[mrpilot2]

Parent PRD

#73

What to build

Introduce the QSortFilterProxyModel in ShowSettingsDialog. Implement logic to filter the settings tree based on the page's display name (case-insensitive). Ensure parent nodes remain visible if a child matches.

Acceptance criteria

• Tree view filters in real-time as user types
• Search is case-insensitive
• Parent nodes remain visible to maintain context
• Clearing search field restores full tree

Blocked by

• Blocked by Infrastructure: Search Field & Signal Routing #74

User stories addressed

• User story 2
• User story 3
• User story 4
• User story 6