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-core/tests/c/harness.c

@@ -0,0 +1,109 @@
+/*
+ * punktfunk-core C ABI harness — M1 acceptance.
+ *
+ * Proves the core links from C and round-trips encoded access units through the full
+ * packetize -> FEC -> in-process loopback (with deterministic packet loss) -> FEC
+ * recover -> reassemble path, recovering every byte exactly.
+ *
+ * Build/run: see tests/c/run.sh (also driven by `cargo test --test c_abi`).
+ */
+#include "punktfunk_core.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static PunktfunkConfig make_config(uint32_t role, uint32_t drop_period) {
+    PunktfunkConfig c;
+    memset(&c, 0, sizeof(c));
+    c.struct_size = (uint32_t)sizeof(PunktfunkConfig);
+    c.role = role;                 /* 0 = host, 1 = client */
+    c.phase = 1;                   /* P1, GameStream-compatible */
+    c.fec_scheme = 0;              /* GF(2^8) */
+    c.fec_percent = 25;
+    c.max_data_per_block = 64;
+    c.shard_payload = 1024;
+    c.max_frame_bytes = 8 * 1024 * 1024;
+    c.encrypt = 0;
+    c.loopback_drop_period = drop_period;
+    return c;
+}
+
+int main(void) {
+    printf("punktfunk-core C ABI harness (abi_version=%u)\n", punktfunk_abi_version());
+
+    const uint32_t DROP_PERIOD = 8;   /* drop 1 of every 8 packets */
+    PunktfunkConfig host_cfg = make_config(0, DROP_PERIOD);
+    PunktfunkConfig client_cfg = make_config(1, DROP_PERIOD);
+
+    PunktfunkSession *host = NULL;
+    PunktfunkSession *client = NULL;
+    PunktfunkStatus rc = punktfunk_test_loopback_pair(&host_cfg, &client_cfg, &host, &client);
+    if (rc != PUNKTFUNK_STATUS_OK || !host || !client) {
+        fprintf(stderr, "FAIL: loopback_pair rc=%d\n", (int)rc);
+        return 1;
+    }
+
+    const size_t FRAME_LEN = 200000;  /* ~196 shards across 4 FEC blocks */
+    const int FRAMES = 4;
+    uint8_t *buf = (uint8_t *)malloc(FRAME_LEN);
+    if (!buf) { fprintf(stderr, "FAIL: oom\n"); return 1; }
+
+    int failures = 0;
+    for (int f = 0; f < FRAMES; f++) {
+        for (size_t i = 0; i < FRAME_LEN; i++) {
+            buf[i] = (uint8_t)((i * 131u) + (unsigned)f * 17u);
+        }
+
+        rc = punktfunk_host_submit_frame(host, buf, FRAME_LEN, (uint64_t)f * 1000000u, 0);
+        if (rc != PUNKTFUNK_STATUS_OK) {
+            fprintf(stderr, "FAIL: submit frame %d rc=%d\n", f, (int)rc);
+            failures++;
+            continue;
+        }
+
+        PunktfunkFrame out;
+        memset(&out, 0, sizeof(out));
+        rc = punktfunk_client_poll_frame(client, &out);
+        if (rc != PUNKTFUNK_STATUS_OK) {
+            fprintf(stderr, "FAIL: poll frame %d rc=%d (expected recovery)\n", f, (int)rc);
+            failures++;
+            continue;
+        }
+        if (out.len != FRAME_LEN || memcmp(out.data, buf, FRAME_LEN) != 0) {
+            fprintf(stderr, "FAIL: frame %d mismatch (len=%zu want=%zu)\n",
+                    f, (size_t)out.len, FRAME_LEN);
+            failures++;
+            continue;
+        }
+        if (out.frame_index != (uint32_t)f) {
+            fprintf(stderr, "FAIL: frame %d wrong index %u\n", f, out.frame_index);
+            failures++;
+        }
+    }
+
+    PunktfunkStats st;
+    memset(&st, 0, sizeof(st));
+    punktfunk_get_stats(client, &st);
+    printf("client stats: completed=%llu recovered_shards=%llu dropped_pkts=%llu rx_pkts=%llu\n",
+           (unsigned long long)st.frames_completed,
+           (unsigned long long)st.fec_recovered_shards,
+           (unsigned long long)st.packets_dropped,
+           (unsigned long long)st.packets_received);
+
+    if (st.fec_recovered_shards == 0) {
+        fprintf(stderr, "FAIL: expected FEC to recover lost shards, but recovered 0\n");
+        failures++;
+    }
+
+    free(buf);
+    punktfunk_session_free(host);
+    punktfunk_session_free(client);
+
+    if (failures == 0) {
+        printf("PASS: %d frames round-tripped byte-exact through lossy loopback\n", FRAMES);
+        return 0;
+    }
+    fprintf(stderr, "FAILED with %d errors\n", failures);
+    return 1;
+}

crates/punktfunk-core/tests/c/run.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# Build punktfunk-core's staticlib, then compile + link + run the C ABI harness against it.
+# Proves the core links from C. Works on Linux and macOS (link flags come from rustc).
+set -euo pipefail
+
+here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ws="$(cd "$here/../../../.." && pwd)"   # tests/c -> crates/punktfunk-core -> crates -> ws
+cd "$ws"
+
+profile="${1:-debug}"
+build_flag=""
+[ "$profile" = "release" ] && build_flag="--release"
+
+echo ">> building punktfunk-core staticlib ($profile)"
+cargo build -p punktfunk-core $build_flag >/dev/null
+
+staticlib="$ws/target/$profile/libpunktfunk_core.a"
+header_dir="$ws/include"
+[ -f "$staticlib" ] || { echo "missing $staticlib"; exit 1; }
+[ -f "$header_dir/punktfunk_core.h" ] || { echo "missing generated header"; exit 1; }
+
+# Ask rustc what native libs the staticlib needs to link into a C program.
+native_libs="$(cargo rustc -p punktfunk-core --lib --crate-type staticlib $build_flag -- \
+    --print native-static-libs 2>&1 | sed -n 's/.*native-static-libs: //p' | tail -1)"
+echo ">> native libs: ${native_libs:-<none>}"
+
+out="$(mktemp -d)/punktfunk_harness"
+cc="${CC:-cc}"
+echo ">> compiling + linking harness"
+$cc -std=c11 -Wall -Wextra -O2 -I "$header_dir" \
+    "$here/harness.c" "$staticlib" $native_libs -o "$out"
+
+echo ">> running"
+"$out"