fix: Exclude S-frames from failed_frames counter

S-frames update lastSlow data (merged into I/P frames) but don't set
parsing_success=true since they don't create separate CSV rows. This
caused them to be incorrectly counted as failed frames.

Fix excludes S-frames from failed_frames increment while keeping the
correct behavior of merging S-frame data into subsequent I/P frames.

Addresses coderabbitai feedback:
- src/parser/frame.rs lines 299-334, 507-513
- src/main.rs lines 1563-1564, 2031-2056

Tested: CLI and CRATE output identical (MD5: 3940efce93a1ef6f48248233357b74cc)

Author: nerdCopter

src/main.rs

@@ -2048,7 +2048,9 @@ fn parse_frames(
                     _ => {}
                 };
 
-                if !parsing_success {
+                // S-frames don't set parsing_success but are processed successfully
+                // (they update lastSlow data merged into I/P frames)
+                if !parsing_success && frame_type != 'S' {
                     stats.failed_frames += 1;
                 }
 

src/parser/frame.rs

@@ -504,7 +504,9 @@ pub fn parse_frames(
                     _ => {}
                 };
 
-                if !parsing_success {
+                // S-frames don't set parsing_success but are processed successfully
+                // (they update lastSlow data merged into I/P frames)
+                if !parsing_success && frame_type != 'S' {
                     stats.failed_frames += 1;
                 }