fix: rename remaining 1_upcoming references to 1_backlog in bot.rs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/matrix/bot.rs

@@ -282,7 +282,7 @@ pub fn build_pipeline_status(project_root: &std::path::Path, agents: &AgentPool)
     let mut out = String::from("**Pipeline Status**\n\n");
 
     let stages = [
-        ("1_upcoming", "Upcoming"),
+        ("1_backlog", "Backlog"),
         ("2_current", "In Progress"),
         ("3_qa", "QA"),
         ("4_merge", "Merge"),
@@ -2084,7 +2084,7 @@ mod tests {
         let dir = tempfile::tempdir().unwrap();
         write_story_file(
             dir.path(),
-            "1_upcoming",
+            "1_backlog",
             "42_story_do_something.md",
             "Do Something",
         );