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>

docs/m2-plan.md

@@ -7,11 +7,11 @@ Ground-truth protocol reference: [`research/gamestream-protocol-research.json`](
 
 ## Architecture (respects the "one core" invariant)
 
-- **lumen-core** gains a **P1 GameStream wire codec** (`ProtocolPhase::P1GameStream`, the
+- **punktfunk-core** gains a **P1 GameStream wire codec** (`ProtocolPhase::P1GameStream`, the
   hook already exists): the exact RTP+`NV_VIDEO_PACKET` framing, the GameStream FEC shard
   layout, and the video/audio AES-GCM/CBC paths. Hot path, native threads, **no async**.
-  Kept beside lumen's native internal format (P2), selected by phase.
-- **lumen-host** gains the **control plane** (tokio/axum OK — I/O-bound, not the hot path):
+  Kept beside punktfunk's native internal format (P2), selected by phase.
+- **punktfunk-host** gains the **control plane** (tokio/axum OK — I/O-bound, not the hot path):
   mDNS discovery, nvhttp serverinfo + the 4-phase pairing, the RTSP handshake, the ENet
   control stream + input injection, the virtual-display lifecycle, and Opus audio encode.
 
@@ -46,16 +46,16 @@ Ground-truth protocol reference: [`research/gamestream-protocol-research.json`](
   the client cert is pinned for subsequent HTTPS. 4 phases over `/pair?phrase=…`.
 - **RTSP** `Session: DEADBEEFCAFE;timeout = 90` (literal), `Transport: server_port=<p>`,
   `streamid=video/0/0` / `control/13/0`. ANNOUNCE carries the negotiated config
-  (`x-nv-video[0].*`, `x-nv-vqos[0].*`) → maps to `lumen_core::Config`.
+  (`x-nv-video[0].*`, `x-nv-vqos[0].*`) → maps to `punktfunk_core::Config`.
 
 ## The two highest interop risks (validate EARLY)
 
 1. **RS-FEC matrix compatibility.** Sunshine + Moonlight both use **nanors** (GF(2⁸), poly
-   0x11d, Vandermonde systematic). lumen-core uses `reed-solomon-erasure` (Cauchy) — parity
+   0x11d, Vandermonde systematic). punktfunk-core uses `reed-solomon-erasure` (Cauchy) — parity
    bytes likely **don't match**, so Moonlight silently fails to recover any frame with a lost
    data shard. Mitigation: **on a clean LAN with no loss the client never runs RS decode**, so
    defer this — get a frame decoded first, then FFI/port nanors for loss recovery.
-2. **Crypto layout.** lumen's `SessionCrypto` (salt + seq-as-AAD) is wire-incompatible. P1
+2. **Crypto layout.** punktfunk's `SessionCrypto` (salt + seq-as-AAD) is wire-incompatible. P1
    needs a separate GameStream GCM path. Mitigation: **video encryption is negotiated and
    usually off on LAN** — implement plaintext video first, add GCM later.
 
@@ -67,8 +67,8 @@ Ground-truth protocol reference: [`research/gamestream-protocol-research.json`](
 - **P1.2 — Launch + RTSP + virtual display.** `/launch` (parse rikey/rikeyid/mode), the RTSP
   handshake, negotiate `Config`, create a wlroots virtual output sized to the client.
   *Acceptance: Moonlight completes RTSP and the host stands up the UDP streams.*
-- **P1.3 — Video (lumen-core P1 codec), plaintext, clean-LAN.** RTP+NV framing + FEC shard
-  layout in lumen-core; wire M0's NVENC AUs → UDP 47998. *Acceptance: Moonlight DISPLAYS video.*
+- **P1.3 — Video (punktfunk-core P1 codec), plaintext, clean-LAN.** RTP+NV framing + FEC shard
+  layout in punktfunk-core; wire M0's NVENC AUs → UDP 47998. *Acceptance: Moonlight DISPLAYS video.*
 - **P1.4 — Control + input.** ENet (`rusty_enet`) control stream; decode input → `inject.rs`
   (uinput/reis); request-IDR → force NVENC keyframe. *Acceptance: mouse/keyboard work.*
 - **P1.5 — Robustness: FEC recovery + encryption.** nanors-exact FEC; per-shard AES-GCM.