fix(mcp): restore hosted keyless Parse safety boundaries

[hmishra2250]

Summary

• reject zeroDataRetention: true after anonymous/keyless session resolution and before any Core eligibility, upload, or Parse endpoint call
• require exactly one syntactically valid source IP from the trusted hosted edge for anonymous keyless traffic (corrected by fix(mcp): preserve trusted proxy keyless identity #335: that source may be an internal ingress address)
• keep redactPII available to anonymous Parse and correct hosted Parse guidance/examples
• lock keyless two-phase Parse, early rejection, forwarded-IP trust, API-key forwarding, and managed-OAuth delegated-credential forwarding with HTTP smoke coverage

Scope

MCP server only. No Core, DB, Infra, endpoint-routing, or Stage-1/2 contract changes.

Regression lineage

The intended guard and tests existed before the PR #308 train but were omitted during the pre-merge reconciliation. This restores the established contract on current main, without a blind revert.

Verification

• npm run build
• targeted hosted smoke: 4 tests pass, including the new Parse regression cases (forwarded-IP deployment compatibility is corrected in fix(mcp): preserve trusted proxy keyless identity #335)
• npm test: 43/43 pass
• npm run lint
• npx tsc --noEmit
• git diff --check

Release verification after merge

firecrawl-mcp-server auto-deploys via GHCR/Keel. From a clean eligible network, verify anonymous tools/list still shows exactly Search/Scrape/Parse; verify anonymous ZDR returns a structured error with no upload instructions; then run a small non-sensitive two-phase Parse fixture and an API-key Parse smoke. Do not log credentials, signed URLs, or upload refs.

Follow-up outside this PR

Infra/security should independently audit lifecycle handling for uploaded-but-never-parsed objects before making stronger retention claims.

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Summary by cubic

Restores the hosted keyless Parse ZDR boundary and tightens client IP trust. Anonymous keyless can still use redactPII; zeroDataRetention: true is denied and multi‑hop/private X-Forwarded-For is not trusted; authenticated sessions can use ZDR.

• Bug Fixes
  • Fail fast on zeroDataRetention in anonymous keyless Parse before any upload or backend call; returns KEYLESS_OPTION_NOT_AVAILABLE with guidance.
  • Require exactly one public client IP from X-Forwarded-For; otherwise reject keyless with KEYLESS_ACCESS_NOT_AVAILABLE. Forward the trusted IP to /v2/keyless/eligibility.
  • Keep redactPII for keyless and update firecrawl_parse docs/examples to note ZDR requires an account or API key.
  • Add HTTP smoke tests to lock behavior: keyless two-phase Parse works without credentials and forwards redactPII; early ZDR rejection; reject multi-hop/private XFF; ZDR allowed and forwarded for API key and managed OAuth sessions.

^{Written for commit f302d83. Summary will update on new commits.}