fix: normalize longDescription ref and correct changeset wording

Two follow-ups to PR #174:

1. Drop the redundant `#main` suffix from the `longDescription` union's
   Leaflet ref in `app.certified.actor.organization`, so it matches the
   bare `pub.leaflet.pages.linearDocument` form already used on activity,
   collection, and attachment after the cleanup in 06fce2c. PR #174 was
   rebased onto that cleanup but re-introduced `#main` for the new
   organization field. Purely a ref-string normalization — the target
   def is identical.

2. Update the unreleased changeset description to describe the actual
   3-way union (inline string / embedded Leaflet linear document /
   strongRef), not a 2-way union, so the v0.12.0 CHANGELOG entry is
   accurate.

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

Author: s-adamantine

.changeset/add-organization-page-and-visibility.md

@@ -2,4 +2,4 @@
 "@hypercerts-org/lexicon": minor
 ---
 
-Add optional `longDescription` and `visibility` fields to `app.certified.actor.organization` lexicon. `longDescription` uses the description union pattern (inline text/markdown or strongRef to a rich-text document) for consistency with activity, collection, and attachment.
+Add optional `longDescription` and `visibility` fields to `app.certified.actor.organization` lexicon. `longDescription` uses the description union pattern — an inline string for plain text or markdown, an embedded Leaflet linear document for rich-text content, or a strong reference to an existing description record — matching the pattern used on activity, collection, and attachment.

lexicons/app/certified/actor/organization.json

@@ -42,7 +42,7 @@
             "type": "union",
             "refs": [
               "org.hypercerts.defs#descriptionString",
-              "pub.leaflet.pages.linearDocument#main",
+              "pub.leaflet.pages.linearDocument",
               "com.atproto.repo.strongRef"
             ],
             "description": "Long-form description of the organization, such as its mission, history, or detailed project narrative. An inline string for plain text or markdown, a Leaflet linear document record embedded directly, or a strong reference to an existing document record."