Stand up the remaining Step 2 families. NetworkSettingsSchema is a
6-branch DU on `network` covering tcp/kcp/ws/grpc/httpupgrade/xhttp, with
asymmetric per-network wire keys (tcpSettings, wsSettings, ...) preserved
exactly so fixtures round-trip byte-identical. SecuritySettingsSchema is a
3-branch DU on `security` covering none/tls/reality. TLS certs use a
file-vs-inline union; uTLS fingerprints are shared between TLS and Reality
via a single primitive enum.
Hysteria-as-network, finalmask, and sockopt are not in the plan's Step 2
inventory and are deferred to Step 6 (Tighten) - they're orthogonal extras
on the stream root, not network-discriminated branches.
Resolves a Security identifier collision in protocols/index.ts by
re-exporting the type alias as SecurityKind (the `Security` name is taken
by the namespace re-export).
