Linux app id: ai.storyteller.solidcraft, with an end-of-life rebase from the old id (#619)

The Flatpak app id, desktop/metainfo/MIME file names, icon name and the window's Wayland app_id / X11 class are now ai.storyteller.solidcraft, the id the ArtCraft launcher expects.

Existing Flatpak installs move over: the Pages repo marks app/ai.storyteller.solvecraft end-of-life with a rebase to the new id, so flatpak update offers the switch and Flatpak carries ~/.var/app along. A new install next to the old one copies settings and autosaves on first launch through a read-only grant on the old data folder. The metainfo declares <replaces>/<provides>, the desktop entry X-Flatpak-RenamedFrom, and AppImages drop the menu entry an older AppImage installed. deb/rpm upgrades remove the old-named files.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packaging/linux/ai.storyteller.solidcraft.mime.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- shared-mime-info definitions for types the system database may not have.
+     Installed to /usr/share/mime/packages/ (update-mime-database runs on install). -->
+<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
+  <mime-type type="application/x-solidcraft">
+    <comment>SolidCraft design</comment>
+    <icon name="ai.storyteller.solidcraft"/>
+    <sub-class-of type="application/json"/>
+    <glob pattern="*.solidcraft"/>
+    <!-- Compatibility shim (docs/compatibility.md): designs saved before the rename. -->
+    <glob pattern="*.solvecraft"/>
+    <alias type="application/x-solvecraft"/>
+  </mime-type>
+</mime-info>