docs(cctv): state what the app does with camera frames (#511)

Supersedes #357 by @Lob26, ported onto the current component layout with fixes from review.

Verified before merge: format, package boundaries, unit suite, build, and the browser tracking suite; a browser harness for the change where one applies; adversarial review applied.

Co-authored-by: Pedro Lobato <[email protected]>

CHANGELOG.md

@@ -223,6 +223,15 @@ of current runtime behavior, see [`docs/CURRENT-STATE.md`](docs/CURRENT-STATE.md
 
 ### Fixed
 
+- `DATA_SOURCES.md` states what the project does with camera frame content: a
+  successful upstream response is relayed as the provider served it, nothing in
+  the camera pipeline enhances it or recognises what is in it, resampling for
+  display is the only change made to the picture, and no frame is written to disk.
+  It also names what a viewer sees when an upstream has no frame — including a
+  last good picture kept after a failed refresh — and the one feature that sends
+  imagery anywhere: the voice assistant's viewport screenshot. Contributed by
+  Lob26 (#357).
+
 - Extract panel disclosure and hover/focus controls into a reusable module;
   cancel their listeners and pending work during replacement and teardown.