Refuse a theme name that is shell syntax, and quote the one the unlock picker returns

A theme installed from a git repo is named after the repo URL, and that name
becomes its directory name under ~/.config/omarchy/themes. Style > Unlock built
a command line out of the name the picker returned and handed it to
omarchy-launch-floating-terminal-with-presentation, which runs its argument as a
shell string -- so a theme directory called `a';id;'b` ran `id`. Themes are
already held to contributing colour and nothing that executes, which is why
omarchy-theme-set stages no .lua, terminal config, or vscode.json from one.

Hold the derived name to the characters a theme name needs, which stops it from
being dangerous at every place it lands rather than at the one found, and quote
it with printf %q on the way into the action for the names already on disk.

omarchy-theme-remove keeps its existing path-climb guard: its name reaches only
a quoted rm, and the same charset would strand a theme installed before this.

Reported-by: Luis Alvarez (lalvarezt)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011WFcUm5HWFyxaVYdwAeWPP

bin/omarchy-theme-install

@@ -29,10 +29,15 @@ REPO_PATH="$REPO_URL"
 THEME_NAME=$(basename -- "$REPO_PATH" .git | sed -E 's/^omarchy-//; s/-theme$//' | tr '[:upper:]' '[:lower:]')
 THEME_PATH="$THEMES_DIR/$THEME_NAME"
 
-# The name comes from the URL and is joined into a path that is about to be
-# removed, so a repo called `..` would take ~/.config/omarchy with it. A leading
-# dot is refused with it: `host:-s/foo.git` leaves basename with `.git`.
-if [[ -z $THEME_NAME || $THEME_NAME == .* || $THEME_NAME == */* ]]; then
+# The name comes from the URL, is joined into a path that is about to be
+# removed, and then names a directory the rest of Omarchy passes around by
+# name: Style > Unlock builds a command line out of the one the picker
+# returned. So it is held to the characters a theme name needs rather than
+# screened for the harm of the day -- a repo called `..` would take
+# ~/.config/omarchy with it, and one called `a';'id` would carry its own
+# command into that picker. The leading character is kept out of `.` and `-`,
+# which also covers `host:-s/foo.git` leaving basename with `.git`.
+if [[ ! $THEME_NAME =~ ^[a-z0-9][a-z0-9._-]*$ ]]; then
   echo "Error: '$REPO_URL' does not give a usable theme name."
   exit 1
 fi