Add cross-platform CA auto-installer and production hardening

- Add cert_installer.py: cross-platform trusted CA installer
  (Windows certutil/PowerShell, macOS security, Linux update-ca-certificates,
  Firefox NSS via certutil/certutil)
- main.py: add --install-cert and --no-cert-check CLI flags; auto-detect and
  auto-install MITM CA on startup when not yet trusted
- mitm.py: rename CA CN/O from 'DomainFront Tunnel' to 'MasterHttpRelayVPN'
- proxy_server.py: downgrade TLS handshake errors to DEBUG to reduce log noise
  for non-HTTPS traffic (MTProto, plain HTTP on non-443 ports)
- README.md / README_FA.md: document new CLI flags, auto-install behaviour,
  and cert_installer.py in project files table

mitm.py

@@ -55,8 +55,8 @@ class MITMCertManager:
             public_exponent=65537, key_size=2048
         )
         subject = issuer = x509.Name([
-            x509.NameAttribute(NameOID.COMMON_NAME, "DomainFront Tunnel CA"),
-            x509.NameAttribute(NameOID.ORGANIZATION_NAME, "DomainFront Tunnel"),
+            x509.NameAttribute(NameOID.COMMON_NAME, "MasterHttpRelayVPN"),
+            x509.NameAttribute(NameOID.ORGANIZATION_NAME, "MasterHttpRelayVPN"),
         ])
         now = datetime.datetime.now(datetime.timezone.utc)
         self._ca_cert = (