Tighten datasheet model matching and keep given fields of view

Codec, product and resolution words never identify a model; generation suffixes such as Mk II no longer fall back to the base model; a mismatched manufacturer never matches, and brand-only numeric names need the brand. The datasheet FOV only fills when the source and seed give none and the pose is not curated, and DATASHEET is shown only while no calibration offset applies. Adds the CC0 extract to DATA_SOURCES.

CHANGELOG.md

@@ -3,10 +3,11 @@
 - CCTV cameras with identified hardware show the model's datasheet specs. When a
   source names a camera model found in the vendored CCTV Camera Database records
   (CC0), the HUD meta line adds its resolution, night vision and PTZ capability.
-  A fixed single-lens model's horizontal FOV replaces the estimate
-  (`FOV n° (DATASHEET)`); a PTZ or varifocal range is what the lens can do, not
-  its current zoom, so those cameras keep the estimate and show
-  `SPEC FOV min–max° (CAPABILITY)` beside it (bassem chagra, #452).
+  A fixed single-lens model's horizontal FOV fills in when the source states no
+  FOV and the pose is not curated (`FOV n° (DATASHEET)`); a PTZ or varifocal
+  range is what the lens can do, not its current zoom, so those cameras keep the
+  estimate and show `SPEC FOV min–max° (CAPABILITY)` beside it (bassem chagra,
+  #452).
 
 - Add WSDOT highway cameras (Washington State) as a keyless CCTV source pack:
   WSDOT's official Travel Center camera layer, with frames registered only on