Rename Wrystr to Vega

Named after Jurij Vega (1754-1802), Slovenian mathematician who made
knowledge accessible through his logarithm tables. Rebrand before
OpenSats application (April 1).

- Product name, window title, identifiers, binary name all renamed
- Cargo package: wrystr -> vega, wrystr_lib -> vega_lib
- PKGBUILD: wrystr -> vega (new AUR package name)
- Release workflow: artifact names, release text updated
- README: new tagline referencing Jurij Vega
- DB migration: auto-renames wrystr.db -> vega.db on first launch
- Keyring service name kept as "wrystr" for backward compatibility
- localStorage keys kept as wrystr_* to preserve existing user data

Pending manual steps:
- Rename GitHub repo hoornet/wrystr -> hoornet/vega
- Create new AUR package vega-git, orphan wrystr-git
- Update local .desktop launcher

squashfs-root/AppRun

@@ -0,0 +1,12 @@
+#! /usr/bin/env bash
+
+# autogenerated by linuxdeploy
+
+# make sure errors in sourced scripts will cause this script to stop
+set -e
+
+this_dir="$(readlink -f "$(dirname "$0")")"
+
+source "$this_dir"/apprun-hooks/"linuxdeploy-plugin-gtk.sh"
+
+exec "$this_dir"/AppRun.wrapped "$@"