Add Larger Viewport Size Options for browser_action Tool

[taeonu]

Current Behavior

The browser_action tool's viewport size maxes out at 1280x800 pixels, causing:

1. Coordinate transformation required: At different zoom levels (e.g., 67%), users must manually transform coordinates (coordinate / 0.67).
2. Multiple screenshots needed: Increases API costs with multiple calls and token processing.
3. Doesn't match modern dev environments: Most developers use larger, high-resolution monitors.
4. Fragmented context for AI: Multiple small screenshots prevent seeing the complete interface at once.

Proposed Solution

Add viewport size options up to 1920x1200 pixels to accommodate common zoom levels.

The viewport size is already configurable via setBrowserViewportSize in ExtensionStateContext.tsx and existing UI settings. Adding larger options should be straightforward.

Benefits

1. Eliminates coordinate transformation: Reduces errors and improves targeting accuracy.
2. Improves UX and productivity: More intuitive tool with less calculation overhead.
3. Reduces API costs: Fewer screenshots means fewer API calls and lower token usage.
4. Provides complete context: Better AI understanding of element relationships and layout.
5. Matches modern dev environments: Aligns with high-resolution monitors used by developers.

Implementation Details

1. Locate viewport size options in UI code
2. 2. Add larger options (1920x1200, 1600x1000)
3. 3. Update UI components
4. 4. Add presets for common zoom levels

Related Issues

Possibly related to #1896 "Browser Preview click always misses target" (same coordinate transformation issue).

Additional Context

Search for "viewport", "browser_action", or "viewportSize" in UI components to locate relevant code.