fix: processor-counts API + ASRX field name conversion

- Fix processor-counts API to correctly read JSON counts:
  - YOLO: use frames.length (was returning null)
  - CUT: prioritize scenes.length over frame_count
  - Result: YOLO 1963 frames, CUT 25 scenes (correct)

- Fix ASRX field name conversion:
  - Convert start_time/end_time → start/end for ASRX compatibility
  - Prefer frame-based positioning over time-based

- Document issues in issues_2026-06-21.md:
  - Issue 6: ASRX field name mismatch
  - Issue 7: processor-counts API null values

src/api/processing.rs

@@ -654,33 +654,51 @@ async fn get_processor_counts(
                 }
             }
 
-            if let Ok(content) = std::fs::read_to_string(&json_path) {
-                if let Ok(json) = serde_json::from_str::<serde_json::Value>(&content) {
-                    frame_count = json
-                        .get("frame_count")
-                        .and_then(|v| v.as_u64())
-                        .map(|v| v as u32);
-                    segment_count = json
-                        .get("segments")
-                        .and_then(|v| v.as_array())
-                        .map(|arr| arr.len() as u32);
-                    chunk_count = json
-                        .get("child_chunks")
-                        .and_then(|v| v.as_array())
-                        .map(|arr| arr.len() as u32)
-                        .or_else(|| {
-                            json.get("parent_chunks")
-                                .and_then(|v| v.as_array())
-                                .map(|arr| arr.len() as u32)
-                        });
-                    if chunk_count.is_none() {
-                        chunk_count = json
-                            .get("chunks")
-                            .and_then(|v| v.as_array())
-                            .map(|arr| arr.len() as u32);
-                    }
-                }
-            }
+if let Ok(content) = std::fs::read_to_string(&json_path) {
+if let Ok(json) = serde_json::from_str::<serde_json::Value>(&content) {
+// CUT: prioritize scenes count over frame_count
+if proc_name == "cut" {
+frame_count = json
+.get("scenes")
+.and_then(|v| v.as_array())
+.map(|arr| arr.len() as u32);
+} else {
+// Standard frame_count field
+frame_count = json
+.get("frame_count")
+.and_then(|v| v.as_u64())
+.map(|v| v as u32);
+
+// YOLO: frames array
+if frame_count.is_none() {
+frame_count = json
+.get("frames")
+.and_then(|v| v.as_array())
+.map(|arr| arr.len() as u32);
+}
+}
+
+segment_count = json
+.get("segments")
+.and_then(|v| v.as_array())
+.map(|arr| arr.len() as u32);
+chunk_count = json
+.get("child_chunks")
+.and_then(|v| v.as_array())
+.map(|arr| arr.len() as u32)
+.or_else(|| {
+json.get("parent_chunks")
+.and_then(|v| v.as_array())
+.map(|arr| arr.len() as u32)
+});
+if chunk_count.is_none() {
+chunk_count = json
+.get("chunks")
+.and_then(|v| v.as_array())
+.map(|arr| arr.len() as u32);
+}
+}
+}
         }
 
         results.push(ProcessorCountInfo {