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/0709/S20709P0.CSV

@@ -0,0 +1,52 @@
+# file,S20709P0.CSV
+# source,BOARD_LOCAL
+# spi,SPI2
+# tick_ms,233842
+# bit,4
+# edge_mode,ORDINARY
+# points,44
+x,y
+272,1
+113,4
+251,10
+174,11
+37,31
+116,33
+118,35
+291,41
+260,55
+175,58
+6,59
+65,66
+257,92
+312,102
+277,103
+217,109
+158,123
+30,124
+62,127
+2,135
+85,136
+275,137
+122,143
+307,166
+17,170
+58,186
+79,192
+160,205
+151,223
+192,225
+265,232
+81,233
+44,249
+153,260
+37,264
+240,271
+36,273
+83,277
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+129,284
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+118,302
+196,306
+271,311