Add queue error handling and status reporting

Introduces structured error tracking for queue-level errors in SweepQueue, including a QueueError dataclass. Adds an is_queued flag to ProgressState and ensures it is set/cleared appropriately as sweeps are added or removed from the queue. Implements comprehensive status() and clear_error() methods for queue state reporting and recovery. Improves error handling for sweep and callable execution, and adds a kill_all() method to fully reset the queue.

Author: caidish

src/measureit/sweep/base_sweep.py

@@ -604,6 +604,7 @@ def update_progress(self) -> None:
             progress=progress_value,
             error_message=self.progressState.error_message,
             error_count=self.progressState.error_count,
+            is_queued=self.progressState.is_queued,
         )
 
     def mark_done(self) -> None:

src/measureit/sweep/progress.py

@@ -17,14 +17,37 @@ class SweepState(Enum):
 
 @dataclass
 class ProgressState:
-    """Lightweight container tracking sweep progress."""
+    """Lightweight container tracking sweep progress.
+
+    Attributes
+    ----------
+    state : SweepState
+        Current state of the sweep (READY, RAMPING, RUNNING, PAUSED, DONE, KILLED, ERROR).
+    time_elapsed : float, optional
+        Time elapsed since sweep started, in seconds.
+    time_remaining : float, optional
+        Estimated time remaining, in seconds.
+    progress : float, optional
+        Progress percentage (0.0 to 1.0).
+    error_message : str, optional
+        Error message if sweep ended in ERROR state.
+    error_count : int
+        Number of errors encountered during sweep execution.
+    is_queued : bool
+        True if the sweep is managed by a SweepQueue (either waiting in queue or
+        currently running as part of queue execution). This allows external tools
+        to distinguish between a sweep that is idle (not yet started) vs one that
+        is part of a queue workflow. Set to True when appended to a SweepQueue,
+        and False when the sweep completes, is killed, or is removed from the queue.
+    """
 
     state: SweepState = SweepState.READY
     time_elapsed: Optional[float] = None
     time_remaining: Optional[float] = None
     progress: Optional[float] = None
     error_message: Optional[str] = None
     error_count: int = 0
+    is_queued: bool = False
 
 
 __all__ = ["ProgressState", "SweepState"]