feat(v0.2): фазовые systemd-таргеты Stage 0/1/2 + splash/warmup + зонтик

P6.3: shturman.target → зонтик (Wants stage0/1/2). Новые: stage0/1/2.target,
shturman-splash.service (Before=shell, минимум зависимостей → «мгновенно»),
shturman-stage2-warmup.service (After=shell, маркер /run/shturman/stage2.ready),
tmpfiles-shturman.conf (/run/shturman). Члены critical set → stage1.target
(WantedBy+PartOf); у shell убран RuntimeDirectory (каталог теперь от tmpfiles).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Alexander <akotenev2003@gmail.com>

systemd/shturman-shell.service

@@ -2,7 +2,7 @@
 Description=Штурман Shell — первый Slint-кадр (software-render → PNG, §6)
 Requires=data.mount shturman-firstboot.service
 After=shturman-power.service shturman-settings.service shturman-machineid.service
-PartOf=shturman.target
+PartOf=shturman-stage1.target
 
 [Service]
 # v0.6: headless software-render кадра в PNG (спека §6 — основной автотест кадра, композитор не нужен).
@@ -10,10 +10,9 @@ PartOf=shturman.target
 # Кадр читает ui.theme/Power с системной шины (After=power/settings) и пишет в tmpfs /run (volatile, A11).
 Type=oneshot
 RemainAfterExit=yes
-RuntimeDirectory=shturman
 ExecStart=/usr/local/bin/shturman-shell --screenshot /run/shturman/frame.png
 TimeoutStartSec=30
 OOMScoreAdjust=-600
 
 [Install]
-WantedBy=shturman.target
+WantedBy=shturman-stage1.target