feat: add capture group support in URL fragment for unique tabs

[sebastienfontaine]

Summary

Add support for regex capture groups in URL fragment for the "Unique" tab feature.

Users can now use placeholders like $1, $2 in the URL fragment field when the "Unique" option is enabled, allowing more flexible duplicate tab detection based on extracted
URL patterns.

Changes

• Add _processUrlFragment() helper function to process capture group placeholders
• Update handleSetUnique() to use processed fragments for comparison
• Pass complete rule object to enable access to url_matcher
• Add comprehensive tests for new functionality

Example Usage

• URL matcher: https://mysite.atlassian.net/browse/([A-Z]+-\d+)
• URL fragment: https://mysite.atlassian.net/browse/$1
• Unique: ✅ enabled

This will detect duplicate tabs for the same JIRA ticket (e.g., ABC-123) regardless of query parameters.

Breaking Changes

None - fully backward compatible with existing rules.

Fixes #457