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>

tests/test_align_export.py

@@ -406,6 +406,40 @@ def test_largest_rect_at_least():
     assert compute.largest_rect_at_least(np.full((3, 4), 2), 2) == (0, 0, 3, 4)
 
 
+def test_largest_rect_matches_brute_force():
+    """Randomized check against an O(n^4) reference.
+
+    The histogram sweep is short and easy to get subtly wrong — an off-by-one in
+    the stack unwind yields rectangles that are merely large, and "large but not
+    maximal" is invisible by eye on real data.
+    """
+    def brute(good):
+        n_rows, n_cols = good.shape
+        best = 0
+        for r0 in range(n_rows):
+            for r1 in range(r0 + 1, n_rows + 1):
+                run = 0
+                for g in good[r0:r1].all(axis=0):
+                    run = run + 1 if g else 0
+                    best = max(best, run * (r1 - r0))
+        return best
+
+    rng = np.random.default_rng(0)
+    for _ in range(200):
+        counts = rng.integers(0, 3, size=(int(rng.integers(1, 9)),
+                                          int(rng.integers(1, 9))))
+        got = compute.largest_rect_at_least(counts, 2)
+        expected = brute(counts >= 2)
+        if got is None:
+            assert expected == 0
+            continue
+        row0, col0, nr, nc = got
+        assert (counts[row0:row0 + nr, col0:col0 + nc] >= 2).all(), \
+            f"rectangle is not pure:\n{counts}\n{got}"
+        assert nr * nc == expected, \
+            f"not maximal ({nr * nc} < {expected}):\n{counts}\n{got}"
+
+
 def test_largest_rect_is_pure_on_the_real_fixture(rig):
     """On real overlap counts the returned rectangle must contain only
     full-overlap pixels — the property a bounding box would violate."""