feat(sources): improve source management with edit mode and auto-fetch name

[Gaubee]

Summary

Improves the source management page with better UX for adding and editing sources.

Changes

1. Edit Mode for Existing Sources

   • Click on any source to enter edit mode
   • Bottom area transforms from "Add" to "Save" mode
   • Selected source is highlighted with ring

2. Auto-fetch Source Name

   • When entering a URL, automatically fetches the source JSON
   • Extracts the name field from the source
   • Shows fetched name as placeholder: "Name (FetchedName)"
   • Falls back to "Custom source" if fetch fails

3. Immediate Refresh After Add/Save

   • Triggers refreshSource() immediately after adding or saving
   • User sees updated data right away

4. New Store Action

   • Added updateSourceName action to ecosystem store

5. Translations

   • Added nameWithDefault key to all locales (en, zh-CN, zh-TW, ar)

Testing

• Type check passes
• Manual testing