Add alignment state indicator and pluggable data sources

- AlignmentThresholds dataclass + VisionEngine.__init__ for injection
- alignment_state computed per snapshot (ready/aligning/fault)
- MonitorPlot circle/vector/legend driven by state color
- Status dot + label moved into POSITION VISUALIZATION panel header
- CsvSessionSource + DemoSource pluggable DataSource layer
- Synthetic DATA/ready/ and DATA/aligning/ sessions for visual testing
- Fix CAM 3 label placement (below circle, not above)

DATA/ready/S20001P0.CSV

@@ -0,0 +1,53 @@
+# saved_on,SYNTHETIC
+# master_file,S20001P0.CSV
+# remote_begin,BEGIN_REMOTE_CSV SOURCE=LOCAL SPI=2 POINTS=49 MODE=SYNTHETIC STATUS=OK
+x,y
+261.57,81.46
+264.32,84.30
+266.98,87.23
+269.54,90.25
+272.00,93.35
+274.35,96.53
+276.61,99.78
+278.75,103.10
+280.78,106.50
+282.70,109.96
+284.51,113.48
+286.20,117.05
+287.78,120.68
+289.23,124.36
+290.56,128.09
+291.77,131.85
+292.86,135.66
+293.82,139.49
+294.66,143.36
+295.37,147.25
+295.95,151.17
+296.40,155.10
+296.72,159.04
+296.92,162.99
+296.98,166.95
+296.92,170.90
+296.72,174.86
+296.40,178.80
+295.95,182.73
+295.37,186.64
+294.66,190.53
+293.82,194.40
+292.86,198.24
+291.77,202.04
+290.56,205.81
+289.23,209.54
+287.78,213.21
+286.20,216.84
+284.51,220.42
+282.70,223.94
+280.78,227.40
+278.75,230.79
+276.61,234.12
+274.35,237.37
+272.00,240.55
+269.54,243.65
+266.98,246.66
+264.32,249.59
+261.57,252.44