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/S10709P0.CSV

@@ -0,0 +1,68 @@
+# file,S10709P0.CSV
+# source,BOARD_LOCAL
+# spi,SPI1
+# tick_ms,194163
+# bit,4
+# edge_mode,ORDINARY
+# points,60
+x,y
+143,4
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+217,17
+136,23
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+138,34
+99,36
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