Implement webview localization for date/time formatting

[Copilot]

This PR addresses the TODO comment in src/common/utils.ts by implementing comprehensive localization support for date/time formatting in all webviews.

Problem

Previously, dayjs was configured with hardcoded English strings for relative time formatting:

dayjs.updateLocale('en', {
  relativeTime: {
    future: 'in %s',
    past: '%s ago',
    s: 'seconds',
    m: 'a minute',
    // ... more hardcoded English strings
  },
});

This prevented proper localization for non-English VS Code users, as webviews would always display timestamps like "2 hours ago" or "a minute ago" in English regardless of the user's locale setting.

Solution

The implementation provides a complete localization pipeline:

1. Localization Keys: Added 15 new keys to package.nls.json for all dayjs relative time strings using VS Code's standard {0} placeholder syntax.

2. Dynamic Configuration: Created createLocalizedRelativeTimeConfig() that uses vscode.l10n.t() to retrieve localized strings based on the user's VS Code language setting.

3. Webview Integration:

   • Extended Issue and CreateParamsNew interfaces with relativeTimeConfig field
   • Updated all webview providers to pass locale configuration during initialization
   • Modified webview contexts to apply the configuration when receiving data

4. Runtime Application: The setLocalizedRelativeTimeConfig() function dynamically updates dayjs configuration, allowing the existing dateFromNow() function to work seamlessly with localized strings.

Key Features

• Universal Coverage: Works across all webviews (PR view, issue view, create PR view)
• Seamless Integration: No changes required to existing dateFromNow() usage or Timestamp component
• Robust Fallback: Gracefully falls back to English strings if localization fails
• VS Code Native: Uses the official vscode.l10n.t() API for consistency with VS Code's localization system

Example

With this change, users with VS Code set to French will now see "il y a 2 heures" instead of "2 hours ago" in webview timestamps, while maintaining full compatibility with all existing functionality.

Created from VS Code via the GitHub Pull Request extension.

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