fix: Correct sequence end time calculation in Gantt charts

Fixes bug where all sequences appeared to run until demo end time instead
of their actual end times in Gantt chart visualizations.

Issue:
- Both ASCII and HTML Gantt generators initialized seq_end to max_time
- This caused all sequences to display full demo duration
- Example: SEQ@0s showed (0-36s) instead of actual (0-2s)

Fix:
- Initialize seq_end to seq_start instead of max_time
- Calculate actual end from effects or explicit [end_time]
- Sequences now show correct duration in visualizations

Before:
  SEQ@0s [pri=0]  (0-36s)    # Wrong - shows full demo duration
  SEQ@2s [pri=0]  (2-36s)    # Wrong

After:
  SEQ@0s [pri=0]  (0-2s)     # Correct - shows actual sequence duration
  SEQ@2s [pri=0]  (2-5s)     # Correct

This makes Gantt charts much more accurate for understanding actual
sequence overlap and timing relationships.

1 files changed, 2 insertions, 2 deletions

diff --git a/tools/seq_compiler.cc b/tools/seq_compiler.cc
index 7ac921f..b61e895 100644
--- a/tools/seq_compiler.cc
+++ b/tools/seq_compiler.cc
@@ -87,7 +87,7 @@ void generate_gantt_chart(const std::string& output_file,
   // Draw sequences and effects
   for (const auto& seq : sequences) {
     float seq_start = std::stof(seq.start_time);
-    float seq_end = max_time;  // Default: runs until end
+    float seq_end = seq_start;  // Start at sequence start
 
     // Check if sequence has explicit end time
     if (seq.end_time != "-1.0") {
@@ -250,7 +250,7 @@ void generate_gantt_html(const std::string& output_file,
   int y_offset = margin_top;
   for (const auto& seq : sequences) {
     float seq_start = std::stof(seq.start_time);
-    float seq_end = max_time;
+    float seq_end = seq_start;  // Start at sequence start
 
     if (seq.end_time != "-1.0") {
       seq_end = seq_start + std::stof(seq.end_time);