Add userColor3 and userColor4 hat colors

[trillium]

Add userColor3 and userColor4 hat colors

Summary

Add two additional user-configurable hat colors (userColor3 and userColor4) to Cursorless. Currently only 2 user-defined colors exist (userColor1/navy and userColor2/apricot), I use 4 colors and as a result am building the extension locally from my personal fork. Would be great if that step wasn't necessary.

Changes

• Talon: Added userColor3 and userColor4 to color enablement defaults and spoken forms (cursorless-talon/src/marks/decorated_mark.py, cursorless-talon/src/spoken_forms.json)
• Type definitions: Extended HatColor union type in all legacy command type files (V0V1, V2, V3)
• Spoken form generation: Added default spoken form mappings for the new colors (cursorless-engine/src/generateSpokenForm/defaultSpokenForms/marks.ts)
• VS Code extension: Added the new colors to all relevant package.json settings — light/dark color values, hat enablement booleans, hat penalties, and color enum list. Default colors: olive green (#6b8e23) and light gray (#e0e0e0)
• Hat styles: Added to the HAT_COLORS const array (hatStyles.types.ts)
• Docs: Updated the user-facing color table in README.md

Both new colors are disabled by default, matching the pattern of userColor1/userColor2.

Test plan

• Verify VS Code loads without errors with default settings
• Enable userColor3 and userColor4 in settings and confirm hats render with the configured colors
• Assign custom spoken form names to the new colors (e.g., "white" → userColor3, "black" → userColor4) since the defaults are placeholder names — users must name their colors to use them
• Confirm existing colors (including userColor1/userColor2) are unaffected
• Run existing test suite