feat(ecosystem): add status tracking for sources + refactor with key-fetch

[Gaubee]

Summary

• Fix SourceItem component missing useTranslation hook (runtime error causing page crash)
• Add status/errorMessage fields to SourceRecord for loading state tracking
• Immediately fetch source after adding subscription
• Show loading/success/error status icons in SourceItem UI
• Display precise timestamp (with seconds) for lastUpdated
• Refactor registry.ts to use @biochain/key-fetch with etag/cache plugins
• Unify SourceRecord type definition (export from stores/ecosystem)

Key Changes

New Fields in SourceRecord

export type SourceStatus = 'idle' | 'loading' | 'success' | 'error';

export interface SourceRecord {
  // ... existing fields
  status: SourceStatus;      // NEW
  errorMessage?: string;     // NEW
}

UI Improvements

• Loading spinner while fetching
• Success checkmark after successful fetch
• Error icon with message on failure
• Precise timestamp (e.g., 2026/1/21 17:39:18)

key-fetch Refactor

Replaced manual fetch + timeout + ETag handling (~100 lines) with declarative key-fetch configuration (~10 lines).