Add HTTPS default tunnel endpoint and outbound connector using Rustls
with mTLS and an additional auth/session token.
- Add rustls, tokio-rustls, hyper, and related dependencies
- Implement TLS config builders (server/client) with cert validation
- Implement HTTPS tunnel listener with mTLS accept and auth handshake
- Implement HTTPS tunnel connector with server cert validation
- Add auth token loading from CLI value or file
- Add security gate state machine for tracking auth progression
- Fail closed for missing/invalid TLS config, cert mismatch, auth failures
- Port conflicts fail without fallback
- Reconnect revalidates all security gates
- 67 tests covering all validation assertions
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