fix: include finish milestones (TT_FinMile) in milestone queries

The list_milestones tool was only returning start milestones (TT_Mile)
and missing all finish milestones. P6 uses two task types for milestones:
- TT_Mile = Start Milestone
- TT_FinMile = Finish Milestone

Changes:
- Update query_milestones() to include both TT_Mile and TT_FinMile
- Derive milestone_type from task_type when not explicitly set:
  - TT_Mile -> 'start'
  - TT_FinMile -> 'finish'
- Add unit tests for milestone_type derivation from task_type

This fixes the E-J Electric schedule returning 5 milestones instead of 62.

src/xer_mcp/parser/table_handlers/task.py

@@ -26,6 +26,22 @@ class TaskHandler(TableHandler):
         float_str = data.get("total_float_hr_cnt", "")
         total_float = float(float_str) if float_str else None
 
+        # Parse milestone_type
+        # First check explicit milestone_type field (MS_Start -> 'start', MS_Finish -> 'finish')
+        # Then derive from task_type (TT_Mile -> 'start', TT_FinMile -> 'finish')
+        raw_milestone_type = data.get("milestone_type", "")
+        task_type = data.get("task_type", "")
+        milestone_type = None
+        if raw_milestone_type:
+            if raw_milestone_type == "MS_Start":
+                milestone_type = "start"
+            elif raw_milestone_type == "MS_Finish":
+                milestone_type = "finish"
+        elif task_type == "TT_Mile":
+            milestone_type = "start"
+        elif task_type == "TT_FinMile":
+            milestone_type = "finish"
+
         return {
             "task_id": data.get("task_id", ""),
             "proj_id": data.get("proj_id", ""),
@@ -42,4 +58,5 @@ class TaskHandler(TableHandler):
             "act_end_date": convert_date(data.get("act_end_date")),
             "total_float_hr_cnt": total_float,
             "driving_path_flag": driving_path,
+            "milestone_type": milestone_type,
         }