feat(929): delete db/yaml_legacy.rs entirely — CRDT is the sole source of truth

Final 929 sweep: every YAML-shaped helper is gone. No production code
parses or writes YAML front matter anywhere.

Surface removed:
- db/yaml_legacy.rs (FrontMatter/StoryMetadata structs, parse_front_matter,
  set_front_matter_field, yaml_residue marker) — file deleted.
- ItemMeta::from_yaml — deleted; callers pass typed ItemMeta::named(...) or
  ItemMeta::default() and use typed CRDT setters (set_depends_on,
  set_blocked, set_retry_count, set_agent, set_qa_mode, set_review_hold,
  set_item_type, set_epic, set_mergemaster_attempted) for the rest.
- write_coverage_baseline_to_story_file + read_coverage_percent_from_json —
  the coverage_baseline YAML field was write-only (nothing read it back);
  removed along with its caller in agent_tools/lifecycle.rs.
- update_story_in_file's generic `front_matter` HashMap parameter —
  tool_update_story now intercepts every known field name and routes it
  to a typed CRDT setter; unknown keys are rejected with an explicit error
  pointing at the typed setters. The function only takes user_story /
  description sections now.
- All 117 ItemMeta::from_yaml callsites migrated. Where tests previously
  passed a YAML-shaped content blob and relied on the helper to extract
  name/depends_on/blocked/agent/qa, they now pass:
    write_item_with_content(id, stage, content, ItemMeta::named("Foo"))
    crate::crdt_state::set_depends_on(id, &[...])    // when needed
    crate::crdt_state::set_blocked(id, true)         // when needed
    crate::crdt_state::set_agent(id, Some("..."))    // when needed
- write_story_content + write_story_file (test helper) now take an
  explicit `name: Option<&str>` instead of parsing it from content.
- db::ops::move_item_stage stopped re-parsing YAML on every stage
  transition; metadata is read straight from the CRDT view when mirroring
  the row into SQLite.

New CRDT setters added for symmetry:
- crdt_state::set_name (mirrors set_agent — explicit name updates).

cargo fmt --check, clippy --all-targets -- -D warnings, and the
2830-test suite all pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/src/http/workflow/story_ops/create.rs

@@ -66,7 +66,7 @@ pub fn create_story_file(
     content.push_str("- TBD\n");
 
     // Write to database content store and CRDT.
-    write_story_content(root, &story_id, "1_backlog", &content);
+    write_story_content(root, &story_id, "1_backlog", &content, Some(name));
 
     // Sync depends_on to the typed CRDT register.
     crate::crdt_state::set_depends_on(&story_id, depends_on.unwrap_or(&[]));
@@ -83,7 +83,6 @@ pub fn create_story_file(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::db::yaml_legacy::parse_front_matter;
     use std::fs;
 
     #[allow(dead_code)]
@@ -146,7 +145,7 @@ mod tests {
             "36_story_existing",
             "1_backlog",
             "---\nname: Existing\n---\n",
-            crate::db::ItemMeta::from_yaml("---\nname: Existing\n---\n"),
+            crate::db::ItemMeta::named("Existing"),
         );
 
         let number = super::super::super::next_item_number(tmp.path()).unwrap();
@@ -184,29 +183,24 @@ mod tests {
     }
 
     #[test]
-    fn create_story_with_colon_in_name_produces_valid_yaml() {
+    fn create_story_with_colon_in_name_persists_to_crdt() {
+        crate::crdt_state::init_for_test();
         let tmp = tempfile::tempdir().unwrap();
         let name = "Server-owned agent completion: remove report_completion dependency";
         let result = create_story_file(tmp.path(), name, None, None, None, None, false);
         assert!(result.is_ok(), "create_story_file failed: {result:?}");
 
         let story_id = result.unwrap();
-        // Read from content store or filesystem.
-        let content = crate::db::read_content(&story_id)
-            .or_else(|| {
-                let backlog = tmp.path().join(".huskies/work/1_backlog");
-                fs::read_to_string(backlog.join(format!("{story_id}.md"))).ok()
-            })
-            .expect("story content should exist");
-
-        let meta = parse_front_matter(&content).expect("front matter should be valid YAML");
-        assert_eq!(meta.name.as_deref(), Some(name));
+        let view =
+            crate::crdt_state::read_item(&story_id).expect("CRDT entry should exist after create");
+        assert_eq!(view.name(), Some(name));
     }
 
     // ── check_criterion_in_file tests ─────────────────────────────────────────
 
     #[test]
-    fn create_story_with_depends_on_writes_front_matter_array() {
+    fn create_story_with_depends_on_persists_to_crdt() {
+        crate::crdt_state::init_for_test();
         let tmp = tempfile::tempdir().unwrap();
         let story_id = create_story_file(
             tmp.path(),
@@ -219,24 +213,9 @@ mod tests {
         )
         .unwrap();
 
-        let contents = crate::db::read_content(&story_id)
-            .or_else(|| {
-                let backlog = tmp.path().join(".huskies/work/1_backlog");
-                fs::read_to_string(backlog.join(format!("{story_id}.md"))).ok()
-            })
-            .expect("story content should exist");
-
-        assert!(
-            contents.contains("depends_on: [489]"),
-            "missing front matter: {contents}"
-        );
-        assert!(
-            !contents.contains("- [ ] depends_on"),
-            "must not appear as checkbox: {contents}"
-        );
-
-        let meta = parse_front_matter(&contents).expect("front matter should parse");
-        assert_eq!(meta.depends_on, Some(vec![489]));
+        let view =
+            crate::crdt_state::read_item(&story_id).expect("CRDT entry should exist after create");
+        assert_eq!(view.depends_on(), &[489]);
     }
 
     // ── Story 730: numeric-only story IDs ─────────────────────────────────────
@@ -258,19 +237,18 @@ mod tests {
     }
 
     #[test]
-    fn create_story_file_writes_type_field_in_front_matter() {
+    fn create_story_file_sets_item_type_register() {
+        crate::crdt_state::init_for_test();
         crate::db::ensure_content_store();
         let tmp = tempfile::tempdir().unwrap();
         let story_id =
             create_story_file(tmp.path(), "Type Test Story", None, None, None, None, false)
                 .unwrap();
-        let content = crate::db::read_content(&story_id).expect("content must exist");
-        let meta = crate::db::yaml_legacy::parse_front_matter(&content)
-            .expect("front matter should be valid");
+        let view = crate::crdt_state::read_item(&story_id).expect("CRDT entry must exist");
         assert_eq!(
-            meta.item_type.as_deref(),
+            view.item_type(),
             Some("story"),
-            "front matter must contain type: story"
+            "CRDT register must be set to story"
         );
     }