Document privacy-minimized Embertop operations

[seoulpro]

What changed

• Recommend a dedicated Nginx access log that omits client IPs, referrers, and query arguments.
• Clarify source-log retention versus Embertop's emitted-event redaction.
• Add loopback-only SSH examples for terminal and web previews, plus service diagnostics.
• Add a parser regression test for the documented log shape.

Why

The previous combined-log example could leave more request metadata on disk than Embertop needs. The new guidance minimizes the dedicated source log while stating that paths and User-Agent remain operational data.

Validation

• npm run typecheck
• npm run lint
• npm run test:unit — 32 passed
• npm test — 39 passed
• npm audit --omit=dev — 0 vulnerabilities