feat: Register WritersLogic CPOP ZWC text watermark (ID 29)

Add zero-width character (ZWC) watermark algorithm for text content
(text/plain, text/markdown, text/html). Embeds HMAC-SHA256 tags as
invisible Unicode characters at deterministic word-boundary positions,
binding document content to CPOP proof-of-process authorship evidence.

Part of the CPOP protocol (draft-condrey-rats-pop).

Author: dcondrey

softbinding-algorithm-list.json

@@ -410,5 +410,21 @@
             "contact": "c2pa@verimatrix.com",
             "informationalUrl": "https://www.verimatrix.com/c2pa/watermarking/"
         }
+    },
+    {
+        "identifier": 29,
+        "alg": "com.writerslogic.zwc-watermark.1",
+        "type": "watermark",
+        "encodedMediaTypes": [
+            "text/plain",
+            "text/markdown",
+            "text/html"
+        ],
+        "entryMetadata": {
+            "description": "WritersLogic CPOP zero-width character (ZWC) watermark for text content. Embeds a truncated HMAC-SHA256 tag as zero-width Unicode characters (U+200B, U+200C, U+200D, U+FEFF) at deterministic word-boundary positions selected via HMAC-seeded Fisher-Yates shuffle. The tag binds the document content hash and Merkle Mountain Range root to the authorship evidence chain, enabling blind extraction without access to the original. Robust against copy-paste and re-encoding; invalidated by content modification (by design, as content changes require re-attestation). Part of the CPOP proof-of-process authorship attestation system implementing draft-condrey-rats-pop",
+            "dateEntered": "2026-03-18T20:00:00.000Z",
+            "contact": "david@writerslogic.com",
+            "informationalUrl": "https://writerslogic.com/cpop/zwc-watermark"
+        }
     }
 ]