Add Node Type Filter for ONNX Models in Search Sidebar

[tnzl]

Problem

When working with large ONNX models, the search sidebar can list thousands of nodes. Filtering by name works, but it's hard to focus on specific operation types (e.g., finding all Conv, MatMul, or GroupQueryAttention nodes). Users had to scroll through many results or type exact names, which is slow for exploratory work.

Solution

Add a node type filter in the search sidebar for ONNX models. A filter icon button appears next to the search input, matching the existing toggle button style. Clicking it opens a dropdown with all unique node types found in the model. Selecting a type filters the results to show only nodes of that type, and it works together with text search for more precise filtering.

Implementation Details

Key Features:

• Filter icon button: A filter icon (three horizontal lines) appears in the search bar for ONNX models, styled like the existing toggle buttons

• Dynamic node type collection: Automatically collects and lists all unique node types from the model (e.g., Conv, MatMul, Add, GroupQueryAttention, Cast, Concat, etc.)

• Dropdown menu: Clicking the filter icon opens a dropdown with:

  • "All Types" option to clear the filter
  • Sorted list of all unique node types
  • Visual indication of the selected type (blue color, bold text)
  • Hover effects for better UX

• Combined filtering: Works with the existing text search — users can filter by type and search by name simultaneously

• ONNX-only: Only appears when viewing ONNX models (detected by checking if model format starts with "ONNX")

• State persistence: Selected filter state is preserved when the sidebar is reopened

Technical Changes:

• Added nodeType to the search state object
• Implemented _collectNodeTypes() method to extract unique node types from the model graph
• Modified _node() filtering logic to respect the node type filter
• Added filter icon SVG symbol (sidebar-icon-filter) to match existing icon style
• Implemented dropdown menu with proper event handling and click-outside-to-close behavior
• Added CSS styling with dark mode support

@lutzroeder , long time user, first PR, please help review.