feat: expand owner/repo shorthand for --install with a --git-host flag

--install someuser/repo expands to https://github.com/someuser/repo;
--git-host overrides the default host and forces source interpretation
even when the value matches an installed bundle name. Two or more path
segments are accepted so nested GitLab-style groups work, and #ref
pinning applies to shorthand values. --uninstall resolves owner/repo
against recorded sources: a single match uninstalls, multiple matches
prompt an interactive selection showing each bundle's source, and
non-interactive runs bail instead of guessing.

src/cli/mod.rs

@@ -187,6 +187,14 @@ pub struct Cli {
         help_heading = "Installation & Updates"
     )]
     pub install: Option<String>,
+    /// Git host used to expand <owner>/<repo> shorthand values passed to --install
+    #[arg(
+        long,
+        value_name = "HOST",
+        requires = "install",
+        help_heading = "Installation & Updates"
+    )]
+    pub git_host: Option<String>,
     /// Reinstall bundled assets, overwriting any local changes
     #[arg(
         long,
@@ -593,6 +601,17 @@ mod tests {
         assert!(parse(&["--install", "https://github.com/x/y", "--install-force"]).install_force);
     }
 
+    #[test]
+    fn parse_git_host_requires_install() {
+        assert!(Cli::try_parse_from(["coyote", "--git-host", "git.x.com"]).is_err());
+        assert_eq!(
+            parse(&["--install", "someuser/omc", "--git-host", "git.x.com"])
+                .git_host
+                .as_deref(),
+            Some("git.x.com")
+        );
+    }
+
     #[test]
     fn help_omits_install_from_and_shows_install_builtins() {
         use clap::CommandFactory;