feat(cli): add 'lore related' semantic similarity command (bd-8con)

Adds 'lore related' / 'lore similar' command for discovering semantically
related issues and MRs using vector embeddings.

Two modes:
- Entity mode: find entities similar to a specific issue/MR
- Query mode: embed free text and find matching entities

Includes distance-to-similarity conversion, label intersection,
human and robot output formatters, and 11 unit tests.

src/core/db.rs

@@ -93,6 +93,10 @@ const MIGRATIONS: &[(&str, &str)] = &[
         "027",
         include_str!("../../migrations/027_tui_list_indexes.sql"),
     ),
+    (
+        "028",
+        include_str!("../../migrations/028_surgical_sync_runs.sql"),
+    ),
 ];
 
 pub fn create_connection(db_path: &Path) -> Result<Connection> {