fix(cli): Ensure new tests can't have invalid components

Previously a freshly created test could contain a component which would later be
ignored by the collector, leading to the creation of tests which are neither
collectable, nor stable, as deletions of temporary directories could destroy
them. This avoids the creation of such tests.

crates/typst-test-cli/src/project.rs

@@ -245,7 +245,14 @@ impl Project {
         let _span = tracing::debug_span!("creating test", test = ?id, ?kind, ?use_template);
 
         if self.tests.contains_key(&id) {
-            anyhow::bail!("Test '{id}' alreayd exists");
+            anyhow::bail!("Test '{id}' already exists");
+        }
+
+        if let Some(reserved) = id
+            .components()
+            .find(|comp| self.resolver.reserved().contains(comp))
+        {
+            anyhow::bail!("Test contains reserved fragment: '{reserved}'")
         }
 
         let source = match (use_template, &self.template) {