fix: default manual_qa to false so stories advance automatically

Bug 283 was implemented with manual_qa defaulting to true, causing all
stories to hold in QA for human review. Changed to default false as
originally specified — stories advance automatically unless explicitly
opted in with manual_qa: true.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/io/story_metadata.rs

@@ -210,15 +210,15 @@ pub fn write_rejection_notes(path: &Path, notes: &str) -> Result<(), String> {
     Ok(())
 }
 
-/// Check whether a story requires manual QA (defaults to true).
+/// Check whether a story requires manual QA (defaults to false).
 pub fn requires_manual_qa(path: &Path) -> bool {
     let contents = match fs::read_to_string(path) {
         Ok(c) => c,
-        Err(_) => return true,
+        Err(_) => return false,
     };
     match parse_front_matter(&contents) {
-        Ok(meta) => meta.manual_qa.unwrap_or(true),
-        Err(_) => true,
+        Ok(meta) => meta.manual_qa.unwrap_or(false),
+        Err(_) => false,
     }
 }
 
@@ -412,10 +412,18 @@ workflow: tdd
     }
 
     #[test]
-    fn requires_manual_qa_defaults_true() {
+    fn requires_manual_qa_defaults_false() {
         let tmp = tempfile::tempdir().unwrap();
         let path = tmp.path().join("story.md");
         std::fs::write(&path, "---\nname: Test\n---\n# Story\n").unwrap();
+        assert!(!requires_manual_qa(&path));
+    }
+
+    #[test]
+    fn requires_manual_qa_true_when_set() {
+        let tmp = tempfile::tempdir().unwrap();
+        let path = tmp.path().join("story.md");
+        std::fs::write(&path, "---\nname: Test\nmanual_qa: true\n---\n# Story\n").unwrap();
         assert!(requires_manual_qa(&path));
     }