Auto-align: level the sample on the DC bias levels from the camera window

The operator frames a good spot, confirms the two DC levels the detector
reads there, and the rig then measures its own tilt: step 1.5 mm either side
on X and then on Y, and tilt the platform until those levels come back.  The
correction that fixes an offset point is the correction that levels the whole
travel — height error and tilt effect are both proportional to the offset —
so the procedure ends by applying it and leaving it applied.

Both directions are measured from the same starting tilt and averaged, which
makes their disagreement a flatness read-out rather than something averaged
away silently.

core/auto_align.py holds the geometry and the search, Qt-free.  The three
T-axes' azimuths are the whole geometry: T1 lies along +X so it alone tilts
along X, and T0/T2 move as an equal-and-opposite pair to tilt along Y without
touching X (tilt_response derives that, and the tests pin it — an axis map
that drifts would still converge, on the wrong axis).  The search is a secant
null on the split-detector difference: probe once to learn what a microstep
is worth, sign included, then step at the null.  It refuses to servo on a
scope that has not re-triggered, escalates a probe that reads as no response
before calling an axis dead, and stops at a per-axis travel limit.

gui/align_bridge.py runs it on a worker thread; stopping is a threading.Event
rather than a queued command, because the worker is inside a long handler for
the whole run.  The camera window carries the button and the progress window,
and locks the scan panel and the jog pads while a run owns the stage.

Adds immediate MEAN measurements and an acquisition count to the scope
driver, and read_bias_mv to core/scope_inspect — the one scalar the
inspection state was missing.

KNOWN_ISSUES.md records what only the rig can settle: the probe step, the
travel limit, the hold current, and whether the piston the X phase applies
alongside its tilt matters.

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

gui/widgets.py

@@ -17,6 +17,14 @@ from PyQt6.QtWidgets import (
 from hardware.serial_util import scored_ports
 
 
+def mono_font(size: int = 11) -> QFont:
+    """Monospace font for numeric read-outs, so columns of digits line up."""
+    font = QFont("Menlo")
+    font.setStyleHint(QFont.StyleHint.Monospace)
+    font.setPointSize(size)
+    return font
+
+
 def set_toggle(btn, checked: bool, text: str, enabled: bool = True):
     """Update a checkable button without re-triggering its toggled signal."""
     btn.blockSignals(True)
@@ -138,10 +146,7 @@ class LogConsole(QWidget):
         self.view = QPlainTextEdit()
         self.view.setReadOnly(True)
         self.view.setMaximumBlockCount(max_blocks)
-        font = QFont("Menlo")
-        font.setStyleHint(QFont.StyleHint.Monospace)
-        font.setPointSize(11)
-        self.view.setFont(font)
+        self.view.setFont(mono_font())
         layout.addWidget(self.view)
 
         row = QHBoxLayout()