Enhanced BaseNode with Hierarchical Circle Indicators + TextNode Implementation #4

Enhance BaseNode component with professional visual identity system and hierarchical indicators, then create TextNode as the first specialized implementation demonstrating the enhanced foundation.

Key Requirements

• Layered circle indicator system (10px solid + 16px semi-transparent background for parents)
• Fixed icon sizing based on app font size (not content font size)
• Top-alignment to node ceiling regardless of content formatting
• SVG icon integration for professional node type indicators
• TextNode specialization with inline editing capabilities
• Hierarchical display patterns with parent-child visual relationships

Dependencies

• Set up Tauri + Svelte project structure #1 (Project Foundation)
• Create design system foundation #2 (Design System)

Sub-Issues

Implement in order: #15, #16, #17, #18, #19, #20

Acceptance Criteria

• BaseNode uses layered circle indicator system instead of emoji
• TextNode component created with inline editing functionality
• Parent nodes show ring effect when they have children
• Icons are fixed-size (16px) and top-aligned regardless of content formatting
• SVG icon system implemented with text icon
• Hierarchical display patterns working (indentation, parent-child relationships)
• Components integrate properly in existing app panels
• All functionality works with light/dark theme switching
• No compilation errors or TypeScript warnings