feat: Add configurable restart policy, default to on-failure

- Changed restart policy from unless-stopped to on-failure
  so Windows shutdown stops the container instead of restarting
- Added RESTART_POLICY env variable to .env.modern and .env.legacy
- Compose files use ${RESTART_POLICY:-on-failure} for flexibility
- Updated WINCTL_GUIDE.md with restart policy documentation
- Updated readme.md with RESTART_POLICY setting

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

compose/server/win2003.yml

@@ -16,5 +16,5 @@ services:
       - 3303:3389/udp
     volumes:
       - ../../data/win2003:/storage
-    restart: unless-stopped
+    restart: ${RESTART_POLICY:-on-failure}
     stop_grace_period: 2m

compose/server/win2008.yml

@@ -16,5 +16,5 @@ services:
       - 3208:3389/udp
     volumes:
       - ../../data/win2008:/storage
-    restart: unless-stopped
+    restart: ${RESTART_POLICY:-on-failure}
     stop_grace_period: 2m

compose/server/win2012.yml

@@ -16,5 +16,5 @@ services:
       - 3212:3389/udp
     volumes:
       - ../../data/win2012:/storage
-    restart: unless-stopped
+    restart: ${RESTART_POLICY:-on-failure}
     stop_grace_period: 2m

compose/server/win2016.yml

@@ -16,5 +16,5 @@ services:
       - 3316:3389/udp
     volumes:
       - ../../data/win2016:/storage
-    restart: unless-stopped
+    restart: ${RESTART_POLICY:-on-failure}
     stop_grace_period: 2m

compose/server/win2019.yml

@@ -16,5 +16,5 @@ services:
       - 3319:3389/udp
     volumes:
       - ../../data/win2019:/storage
-    restart: unless-stopped
+    restart: ${RESTART_POLICY:-on-failure}
     stop_grace_period: 2m

compose/server/win2022.yml

@@ -16,5 +16,5 @@ services:
       - 3322:3389/udp
     volumes:
       - ../../data/win2022:/storage
-    restart: unless-stopped
+    restart: ${RESTART_POLICY:-on-failure}
     stop_grace_period: 2m

compose/server/win2025.yml

@@ -16,5 +16,5 @@ services:
       - 3325:3389/udp
     volumes:
       - ../../data/win2025:/storage
-    restart: unless-stopped
+    restart: ${RESTART_POLICY:-on-failure}
     stop_grace_period: 2m