Add current-draft diagnostic underlines and passive hover

Preserve raw include diagnostic provenance and derive bands from the existing shaped editor. Retain deferred tooltip paragraphs through rendering. Include source, regression, failure and native-trial evidence; corrected native acceptance remains pending.

crates/oa-cli/src/lib.rs

@@ -222,8 +222,8 @@ pub fn prepare(entry: &Path, operation: Operation) -> Result<Prepared, Box<Repor
         Box::new(report.clone())
     })?;
     let raw = snapshot.reachable_bundle();
-    // The loader may include warnings from stabilized compilation. Only its
-    // discovery/IO diagnostics are authoritative on the original bytes.
+    // Keep discovery/IO failures that lint cannot recover from the bundle alone.
+    // Recompute source diagnostics below, against the same original bytes.
     let mut diagnostics: Vec<_> = snapshot
         .diagnostics
         .iter()