rename: lumen → punktfunk, everywhere

Full project rename, decided 2026-06-10:
- Crates/binaries: punktfunk-core / punktfunk-host / punktfunk-client-rs.
- C ABI: punktfunk_* symbols, Punktfunk* types, include/punktfunk_core.h,
  PUNKTFUNK_FEATURE_QUIC guard (header regenerated; cbindgen renames updated, incl.
  PUNKTFUNK_BTN_*/PUNKTFUNK_AXIS_* wire constants).
- Protocol: punktfunk/1 — control-plane magic LMN1 → PKF1, nonce salt lmn1 → pkf1.
  WIRE BREAK: clients must be rebuilt from this revision.
- Env knobs: PUNKTFUNK_VIDEO_SOURCE / PUNKTFUNK_COMPOSITOR / PUNKTFUNK_ZEROCOPY / ….
- Host config dir: ~/.config/punktfunk (the box's dir was migrated in place — the
  persistent identity is unchanged, pinned fingerprints stay valid).
- Swift package: PunktfunkKit + PunktfunkCore.xcframework + PunktfunkConnection
  (Sources/PunktfunkClient app + tests renamed with it); build-xcframework.sh updated.
- scripts/: 60-punktfunk.rules, punktfunk-host.service; OpenAPI doc regenerated.

Also: scripts/headless/run-headless-kde.sh — full headless Plasma bringup. Root cause of
"desktop but no apps/settings" over the stream: plasmashell launched without
XDG_MENU_PREFIX=plasma-, so the launcher resolved a nonexistent applications.menu and
rendered an empty menu. The script sets the complete KDE session env (menu prefix,
KDE_FULL_SESSION, session version) and rebuilds ksycoca before starting plasmashell.

Gate: 97/97 tests, clippy -D warnings (both feature sets), fmt, C-ABI harness PASS,
zero lumen references left outside .git.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/punktfunk-host/src/gamestream/tls.rs

@@ -0,0 +1,99 @@
+//! TLS for the HTTPS nvhttp port (47984). Moonlight does **mutual TLS** — it presents its
+//! client cert and expects the server to request one — so a plain server-auth config makes
+//! the post-pairing `pairchallenge` fail. This config requests the client cert and verifies
+//! the client owns its key, but (for now) accepts any well-formed cert; enforcing the
+//! paired allow-list (rejecting unpaired clients on /launch) is a follow-up hardening step.
+
+use anyhow::{anyhow, Context, Result};
+use rustls::client::danger::HandshakeSignatureValid;
+use rustls::crypto::{verify_tls12_signature, verify_tls13_signature, CryptoProvider};
+use rustls::pki_types::{CertificateDer, UnixTime};
+use rustls::server::danger::{ClientCertVerified, ClientCertVerifier};
+use rustls::{DigitallySignedStruct, DistinguishedName, ServerConfig, SignatureScheme};
+use std::sync::Arc;
+
+/// Requests + signature-checks the client cert but accepts any (the pairing handshake is
+/// the real proof). Pinning to the paired set is a hardening follow-up.
+#[derive(Debug)]
+struct AcceptAnyClientCert {
+    provider: Arc<CryptoProvider>,
+}
+
+impl ClientCertVerifier for AcceptAnyClientCert {
+    fn offer_client_auth(&self) -> bool {
+        true
+    }
+
+    fn client_auth_mandatory(&self) -> bool {
+        true
+    }
+
+    fn root_hint_subjects(&self) -> &[DistinguishedName] {
+        &[]
+    }
+
+    fn verify_client_cert(
+        &self,
+        _end_entity: &CertificateDer,
+        _intermediates: &[CertificateDer],
+        _now: UnixTime,
+    ) -> Result<ClientCertVerified, rustls::Error> {
+        Ok(ClientCertVerified::assertion())
+    }
+
+    fn verify_tls12_signature(
+        &self,
+        message: &[u8],
+        cert: &CertificateDer,
+        dss: &DigitallySignedStruct,
+    ) -> Result<HandshakeSignatureValid, rustls::Error> {
+        verify_tls12_signature(
+            message,
+            cert,
+            dss,
+            &self.provider.signature_verification_algorithms,
+        )
+    }
+
+    fn verify_tls13_signature(
+        &self,
+        message: &[u8],
+        cert: &CertificateDer,
+        dss: &DigitallySignedStruct,
+    ) -> Result<HandshakeSignatureValid, rustls::Error> {
+        verify_tls13_signature(
+            message,
+            cert,
+            dss,
+            &self.provider.signature_verification_algorithms,
+        )
+    }
+
+    fn supported_verify_schemes(&self) -> Vec<SignatureScheme> {
+        self.provider
+            .signature_verification_algorithms
+            .supported_schemes()
+    }
+}
+
+/// Build a mutual-TLS `ServerConfig` presenting the host cert/key.
+pub fn server_config(cert_pem: &str, key_pem: &str) -> Result<Arc<ServerConfig>> {
+    let provider = Arc::new(rustls::crypto::aws_lc_rs::default_provider());
+    let certs = rustls_pemfile::certs(&mut cert_pem.as_bytes())
+        .collect::<std::result::Result<Vec<_>, _>>()
+        .context("parse host cert PEM")?;
+    let key = rustls_pemfile::private_key(&mut key_pem.as_bytes())
+        .context("parse host key PEM")?
+        .ok_or_else(|| anyhow!("no private key in host key PEM"))?;
+
+    let verifier = Arc::new(AcceptAnyClientCert {
+        provider: provider.clone(),
+    });
+    let config = ServerConfig::builder_with_provider(provider)
+        .with_safe_default_protocol_versions()
+        .context("rustls protocol versions")?
+        .with_client_cert_verifier(verifier)
+        .with_single_cert(certs, key)
+        .context("rustls server cert")?;
+    Ok(Arc::new(config))
+}