docs: fix security and dependency documentation

[galligan]

Summary

Security and dependency documentation contains inaccuracies about automation and feature flags.

Findings

Issue ID	Description
SEC-001	SECURITY.md claims automated security checks but GitHub workflow is manual-only
DEPS-001	DEPS.md - Incorrect reqwest features (docs: rustls-tls, actual: rustls-tls-webpki-roots)
DEPS-002	DEPS.md - Incorrect pprof features (docs: flamegraph, actual: none specified)

Files to Update

• SECURITY.md - Clarify that security audits are manual
• DEPS.md - Update feature flags to match Cargo.toml

Source of Truth

• Cargo.toml (workspace root)
• .github/workflows/ for CI configuration

Priority

Critical - Security claims should be accurate.

[linear]

BLZ-314