Refresh CLAUDE.md for 2.0; link changelog from the version in About

- Rewrite the stale CoreData/CloudKit architecture docs to describe the
  2.0 iCloud Drive document architecture (JSON source of truth + SwiftData
  cache, SyncEngine/ICloudFileManager/ICloudFileMonitor, ULID document/
  entity/mapper split, AppServices DI, WatchConnectivity bridge, XcodeGen/
  Swift 6/iOS 26, real directory layout).
- Add an "Authoring the Changelog" section documenting the end-user,
  one-paragraph-per-entry, derive-but-rewrite-from-git-log convention.
- About screen: make the version line open the changelog (IndieAbout
  0.2.0 changelogDocument) and drop the separate "Changelog" link; bump
  the IndieAbout dependency to from: 0.2.0.

Claude-Session: https://claude.ai/code/session_01A9CfUa4E9Zd5swfoNsYPs7

project.yml

@@ -18,7 +18,7 @@ settings:
 packages:
   IndieAbout:
     url: https://git.rzen.dev/rzen/indie-about.git
-    from: "0.1.0"
+    from: "0.2.0"
   Yams:
     url: https://github.com/jpsim/Yams
     from: "6.0.0"