v2.0.0: claims model - signed MMUR2 votes in a truth DB, merged view in a rebuildable cache DB; POST /api/claims, claims and merge routes, unsigned writes answer 410

Dockerfile

@@ -6,7 +6,8 @@
 # - Bash-based leader election script (flock on shared volume)
 # - meta-core Go binary (HTTP API, Mount API, Watcher)
 # - nginx (dashboard, WebDAV, API proxy)
-# - SQLite metadata store, embedded in the Go binary (/meta-core/db/meta-core.db)
+# - SQLite metadata store, embedded in the Go binary: truth /meta-core/db/meta-core.db
+#   (signed claims, backed up) + cache /meta-core/db-cache/cache.db (rebuildable)
 # - rclone (single mount executor — SMB goes through rclone's :smb: backend)
 # - supervisord (process management - runs on leader only)
 #
@@ -105,6 +106,7 @@ RUN chmod +x /usr/local/bin/meta-core
 RUN mkdir -p \
     /meta-core/locks \
     /meta-core/db \
+    /meta-core/db-cache \
     /meta-core/services \
     /meta-core/mounts/errors \
     /files \