feat: add global search functionality

[vishaltps]

Summary

• Add unified search feature that allows users to search across all job types from a single search box in the header
• Search is accessible from any page via the header search box
• Results are grouped by category (Ready, Scheduled, Failed, In Progress, Completed, Recurring Tasks)

Features

• Global search box in header - accessible from any page
• Searches across all job types: Ready, Scheduled, Failed, In Progress, Completed jobs, and Recurring Tasks
• Searchable fields: class name, queue name, arguments, job ID, error messages, recurring task keys
• Case-insensitive search with SQL injection protection
• Results grouped by category with counts
• Clickable header title links to overview page
• Search query persists in header search box

New Files

File	Purpose
app/services/solid_queue_monitor/search_service.rb	Core search logic
app/controllers/solid_queue_monitor/search_controller.rb	Handles /search route
app/presenters/solid_queue_monitor/search_results_presenter.rb	Renders grouped results

Test Plan

• All 207 tests pass (53 new tests for search functionality)
• Manual testing completed - search works for all job types
• Completed jobs are searchable by job ID and arguments
• Header search box shows current query on search results page