Release secrets-mcp 0.3.0: folder/type schema and MCP folder disambiguation

- Rename namespace/kind to folder/type on entries, audit_log, and history tables;
  add notes. Unique key is (user_id, folder, name).
- Service layer and MCP tools support name-first lookup with optional folder when
  multiple entries share the same name.
- secrets_delete dry_run uses the same disambiguation as real deletes.
- Add scripts/migrate-v0.3.0.sql for manual DB migration. Refresh README and
  AGENTS.md.

Made-with: Cursor

Cargo.lock

@@ -1968,7 +1968,7 @@ dependencies = [
 
 [[package]]
 name = "secrets-mcp"
-version = "0.2.2"
+version = "0.3.0"
 dependencies = [
  "anyhow",
  "askama",