Build Trigger

• Added support for named, site-independent build hooks (e.g. “Production”, “Staging”) via the new Additional build hooks setting. These appear in the trigger dropdown alongside per-site hooks. (#3)
• Named hook URLs support environment variables and aliases, just like per-site hooks.

• Added support for configuring a separate build hook URL per site (multisite).
• Build hook URLs now support environment variables and aliases (e.g. $BUILD_HOOK_MAIN).
• The Build Trigger section now lets you pick a site and trigger its build.
• Build hook requests now accept any 2xx response (services such as Netlify and Vercel often return 201) and handle request failures gracefully.
• Existing single-URL configurations are automatically migrated to the primary site.

The buildHookUrl setting has been replaced by a per-site buildHookUrls map. Existing configurations are migrated automatically to the primary site on update.

• Initial release