feat: Add is_extended_promotional column to all component tables

[buildingvibes]

Summary

• Added is_extended_promotional column to the Component database interface
• Updated BaseComponent interface to include is_extended_promotional field
• Added is_extended_promotional column definition and mapping to all 37 derived component tables
• Created database index optimization for the extended_promotional column for faster queries
• Updated components/list route to support filtering by extended promotional status
• Updated api/search endpoint to support is_extended_promotional query parameter

Context

Extended promotional parts are components that act as basic parts for a limited time period. Having this information available as a filterable column allows users to:

• Identify parts with temporary promotional pricing
• Optimize component selection for cost savings
• Better plan for long-term availability

This implementation follows the same pattern as is_basic and is_preferred columns, ensuring consistency across the codebase.

Changes

1. Database Schema: Added extended_promotional column to the components table in kysely types
2. Derived Tables: Updated all 37 component type tables to include the new column
3. Index Optimization: Created idx_components_extended_promotional index for query performance
4. API Routes: Added filtering support in both the components list UI and search API
5. UI: Added checkbox filter for extended promotional parts in the components list page

Testing

The implementation follows the exact same pattern as the existing is_preferred column (added in #99), ensuring compatibility with the current architecture.

Fixes #92
/claim #92

[buildingvibes]

Note: The 2 test failures in CI are pre-existing and unrelated to this PR's changes. They're caused by a missing kysely-d1 package dependency:

error: Cannot find package 'kysely-d1' from '/home/runner/work/jlcsearch/jlcsearch/cf-proxy/src/db/get-d1-client.ts'

All 84 other tests pass, and the format-check and type-check CI jobs both pass successfully.