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>

clients/apple/Sources/PunktfunkClient/SessionModel.swift

@@ -0,0 +1,115 @@
+// Session state for the app shell: owns the connection, the input capture, and the
+// pump-thread → main-actor stats relay.
+
+import Foundation
+import PunktfunkKit
+import SwiftUI
+
+/// Pump-thread-side frame counters; a 1 Hz main-actor timer drains them into @Published
+/// values. NSLock instead of an actor — the writer is the (non-async) pump thread.
+final class FrameMeter: @unchecked Sendable {
+    private let lock = NSLock()
+    private var frames = 0
+    private var bytes = 0
+    private var totalFrames = 0
+
+    func note(byteCount: Int) {
+        lock.lock()
+        frames += 1
+        bytes += byteCount
+        totalFrames += 1
+        lock.unlock()
+    }
+
+    /// Returns and resets the per-interval counters (the running total stays).
+    func drain() -> (frames: Int, bytes: Int, total: Int) {
+        lock.lock()
+        defer {
+            frames = 0
+            bytes = 0
+            lock.unlock()
+        }
+        return (frames, bytes, totalFrames)
+    }
+}
+
+@MainActor
+final class SessionModel: ObservableObject {
+    @Published var connection: PunktfunkConnection?
+    @Published var connecting = false
+    @Published var errorMessage: String?
+    @Published var fps = 0
+    @Published var mbps = 0.0
+    @Published var totalFrames = 0
+
+    let meter = FrameMeter()
+    private var inputCapture: InputCapture?
+    private var statsTimer: Timer?
+
+    func connect(host: String, port: UInt16, width: UInt32, height: UInt32, hz: UInt32) {
+        guard !connecting else { return }
+        connecting = true
+        errorMessage = nil
+        Task.detached(priority: .userInitiated) {
+            // PunktfunkConnection.init blocks on the QUIC handshake — keep it off the main actor.
+            let result = Result { try PunktfunkConnection(
+                host: host, port: port, width: width, height: height, refreshHz: hz) }
+            await MainActor.run { [weak self] in
+                guard let self else { return }
+                self.connecting = false
+                switch result {
+                case .success(let conn):
+                    self.connection = conn
+                    self.startInput(conn)
+                    self.startStatsTimer()
+                case .failure:
+                    self.errorMessage = "Connection failed — is the host running? " +
+                        "(punktfunk-host m3-host on \(host):\(port))"
+                }
+            }
+        }
+    }
+
+    func disconnect() {
+        inputCapture?.stop()
+        inputCapture = nil
+        statsTimer?.invalidate()
+        statsTimer = nil
+        if let conn = connection {
+            // close() waits out an in-flight poll (≤100 ms) and joins the Rust worker
+            // threads — keep that off the main actor.
+            Task.detached { conn.close() }
+        }
+        connection = nil
+        fps = 0
+        mbps = 0
+    }
+
+    /// Called (via the main actor) when the pump hits end-of-session.
+    func sessionEnded() {
+        guard connection != nil else { return }
+        disconnect()
+        errorMessage = "Session ended by host."
+    }
+
+    private func startInput(_ conn: PunktfunkConnection) {
+        let capture = InputCapture(connection: conn)
+        capture.start()
+        inputCapture = capture
+    }
+
+    private func startStatsTimer() {
+        let timer = Timer(timeInterval: 1.0, repeats: true) { [weak self] _ in
+            guard let self else { return }
+            Task { @MainActor in
+                let (frames, bytes, total) = self.meter.drain()
+                self.fps = frames
+                self.mbps = Double(bytes) * 8 / 1_000_000
+                self.totalFrames = total
+            }
+        }
+        // .common so the HUD keeps updating during window drags / menu tracking.
+        RunLoop.main.add(timer, forMode: .common)
+        statsTimer = timer
+    }
+}