Replace the two Fusion alignment actions with a three-step wizard

Alignment was two disconnected menu actions. `Angle Alignment` ran the
registration with ref_angle_idx hard-coded to 0, no exposed parameters and
no way to retry; `Manual Alignment...` was a separate dialog that
deliberately refused to inherit the automatic result, so a bad fit meant
starting over by hand. Neither told you whether the alignment was any
good, and neither produced anything durable beyond an in-memory result.

Fusion -> Alignment Wizard... now covers all of it in three steps:

  1. Correlate. Reference angle, DC threshold, source, rotation seed and
     sign, search window, coarse step and fine grid are all on the page,
     and Run/Re-run is repeatable. Angles start pre-rotated from the
     stage angles in the file, so the page is informative before any
     correlation runs. The verdict is a picture: every angle's DC mask
     reprojected onto the shared canvas and summed, coloured by how many
     angles cover each pixel, so a good alignment reads as one saturated
     plateau and a bad one as a fringe of low-count halos. A per-angle
     fit table flags angles that did not register or that disagree with
     their stage angle by more than a degree.
  2. Crop. An axis-aligned rectangle on that canvas, with numeric
     canvas-pixel boxes synced both ways and a live size estimate.
     "Fit to full overlap" uses a largest-rectangle sweep rather than a
     bounding box: the overlap region of several rotated scans is roughly
     a disc, whose bounding box has corners no angle covers.
  3. Save. Writes the aligned, cropped stack to a new .sras.

Because the wizard replaces both actions it absorbs the old dialog's
by-eye nudge editor — without it, a scan the search cannot fit would
have no fallback at all. ManualAlignmentDialog is therefore deleted
rather than left orphaned, and its tests move to the wizard.

Two bugs found while driving it end to end and fixed here: QSpinBox
setRange clamps and emits valueChanged, which committed a 1x1 crop
before the default preset could run; and the mm round trip returns an
exact pixel boundary as 11.000000000000002, so a bare ceil() added a
spurious column on every rectangle edit.

Verified: 103 pass, the 6 test_stored_cache failures are pre-existing on
main, and tools/check_equivalence.py is byte-identical to main.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

sras_workers.py

@@ -16,9 +16,7 @@ from PyQt6.QtCore import QObject, pyqtSignal
 
 import sras_compute as compute
 from sras_align_export import write_aligned_sras
-from sras_compute import (
-    cache_file, compute_angle_alignment, compute_rf_image, dc_image_mv,
-)
+from sras_compute import cache_file, compute_rf_image, dc_image_mv
 from sras_format import CH3_IDX, CH4_IDX, SrasFile
 
 # Concurrency caps. Batch conversion runs one process per file, and each of
@@ -302,34 +300,9 @@ class BatchCacheWorker(QObject):
         self.finished.emit()
 
 
-class AngleAlignmentWorker(QObject):
-    """Computes the rigid (rotation + translation, never scale) alignment for
-    every angle in *sras* against *ref_angle_idx*, by cross-correlating each
-    angle's CH4 image against the reference's. Both the rotation and the
-    translation are found from image content — see compute_angle_alignment.
-    """
-    progress = pyqtSignal(int)             # 0–100
-    finished = pyqtSignal(object, str)     # AlignmentResult|None, error ("" = success)
-
-    def __init__(self, sras: SrasFile, ref_angle_idx: int, dc_threshold_mv: float):
-        super().__init__()
-        self._sras = sras
-        self._ref = ref_angle_idx
-        self._threshold = dc_threshold_mv
-
-    def run(self):
-        try:
-            result = compute_angle_alignment(
-                self._sras, self._ref, self._threshold,
-                progress_cb=self.progress.emit)
-            self.finished.emit(result, "")
-        except Exception as exc:
-            self.finished.emit(None, str(exc))
-
-
 class Ch4MaskWorker(_PooledWorker):
-    """Fetches each requested angle's CH4 (Bias B) DC image in mV, for
-    ManualAlignmentDialog's initial threshold-mask overlay.
+    """Fetches each requested angle's CH4 (Bias B) DC image in mV, for the
+    alignment wizard's initial threshold-mask stack.
 
     Reuses dc_image_mv, which prefers a stored v5/v7 cache over recomputing
     from raw waveforms, so this only does real work for a file that hasn't
@@ -338,7 +311,7 @@ class Ch4MaskWorker(_PooledWorker):
     every file load) hasn't reached yet. In the common case — the user opens
     Fusion -> Manual Alignment after DC precompute has already finished —
     *angle_indices* is empty and this worker is never even constructed (see
-    ManualAlignmentDialog._start_mask_prep).
+    CorrelatePage._start_mask_prep).
     """
     angle_done = pyqtSignal(int, np.ndarray)   # angle_idx, dc4_mv
 
@@ -365,8 +338,8 @@ class Ch4MaskWorker(_PooledWorker):
 
 class CrossCorrelateWorker(_PooledWorker):
     """Rigid registration (rotation + translation, never scale) of each of
-    *angle_indices* against *ref_angle_idx*, for ManualAlignmentDialog's Auto
-    Cross-Correlate button.
+    *angle_indices* against *ref_angle_idx*, for the alignment wizard's
+    Run/Re-run Correlation button.
 
     Runs on a background thread — registering a real many-angle,
     high-resolution scan takes long enough that doing it on the GUI thread