fix(identify): attribute C2PA by claim_generator, not incidental issuer tokens (v0.6.1)

Verified on real signed files that the issuer byte-scan mis-attributes
multi-entity manifests: Leica read as "Truepic" (timestamp authority in the
chain), Nikon as "Adobe Firefly" (XMP-toolkit "Adobe" + the sample's
"Adobe_MAX" name), Truepic as "Google". Platform attribution now prefers the
claim generator (what produced the asset) and falls back to the issuer scan.

- New _CLAIM_GENERATOR_PLATFORM map + _platform_from_generator; claim generator
  read for non-PNG via the now-public c2pa.cbor_text_after.
- Device tokens listed only where verified against a real C2PA file (Leica
  lc_c2pa, Nikon, Truepic Lens); Pixel/Samsung/Sony/Canon/Bria deferred until a
  real sample confirms the in-manifest string. Camera C2PA marks capture
  authenticity, so these never set is_ai.
- cbor_text_after made public (was _cbor_text_after); call sites + tests updated.
- Regression test: claim_generator beats incidental Adobe/Google/Truepic tokens.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

uv.lock

@@ -2784,7 +2784,7 @@ wheels = [
 
 [[package]]
 name = "remove-ai-watermarks"
-version = "0.6.0"
+version = "0.6.1"
 source = { editable = "." }
 dependencies = [
     { name = "click" },