fix: JWT log redaction, resilient parallel health checks, operator-only health detail

[ANTIDOT20]

Closes #543
Closes #544
Closes #545
Closes #546

Changes

• [security] JWT sign method logs wallet address on every token issuance #543: JwtService.sign no longer logs the wallet address, and signWithRole logs only the role. The auth controller's existing login log remains the single place a wallet is recorded.
• [bug] Health controller does not handle Redis connection failure gracefully #544: every Redis call in the health check (PING, queue depth, worker heartbeats, memory info) is bounded by the existing 3s probe timeout, so an unreachable Redis that would otherwise leave commands queued reports queue status error instead of hanging the endpoint.
• [perf] Health controller runs all checks sequentially #545: the database, Stellar, Redis and external-API checks now run in parallel through Promise.all. Checks inside each group keep their original order, so the combined error messages are unchanged.
• [security] Health endpoint exposes internal infrastructure details #546: unauthenticated callers get overall status plus per-component status only. Pool stats, throughput, replication lag, keeper balance, RPC details, Redis memory, worker heartbeats, queue depths and component versions are returned only when the operator API key (x-api-key, same key as the operator guard) is presented; comparison is constant-time. Specs cover both views.

Scope notes

• The detailed view uses the operator API key only; admin bearer tokens are not accepted for it.
• Existing health specs still call check() without a request object; only the new specs pass one.
• src/policy/policy.controller.ts already fails to parse on main (unrelated to this change), and the Prisma client was not generated locally, so a full typecheck was not possible; the changed files showed no errors other than the missing generated Prisma types.

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