- Removed duplicate #endregion in backend.Dockerfile (P6 critical)
- Added @RATIONALE and @REJECTED to install_ca_to_nss and install_llm_ca_certs
- Changed grep -q to grep -qF in install_llm_ca_certs validation
- install_ca_to_nss() — imports corporate CA certs into Chromium's NSS
database (~/.pki/nssdb), fixing ERR_CERT_AUTHORITY_INVALID in Playwright
- libnss3-tools added to Dockerfile for certutil binary
