Repair stats/indexer specs; declare @pinata/sdk and express

[Mordy7]

Closes #1385
Closes #1386
Closes #1387
Closes #1388

• stats.service.spec.ts: rebuilt from the stitched merge into one balanced suite, constructed with a real StatsCacheService and typed mocks (no as any)
• indexer.service.spec.ts: typed the record mock as jest.fn(async () => undefined)
• package.json / package-lock.json: declared @pinata/sdk and express; added ipfs.service.pinata.spec.ts covering the non-dev-mode constructor path
• Lockfile regenerated with npm install --package-lock-only (nothing installed); tests and build were not run

The stats spec needs the stats.service.ts repair from #1381-1384 to compile.

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