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

crates/secrets-core/src/service/import.rs

@@ -47,10 +47,9 @@ pub async fn run(
     for entry in &data.entries {
         let exists: bool = sqlx::query_scalar(
             "SELECT EXISTS(SELECT 1 FROM entries \
-             WHERE namespace = $1 AND kind = $2 AND name = $3 AND user_id IS NOT DISTINCT FROM $4)",
+             WHERE folder = $1 AND name = $2 AND user_id IS NOT DISTINCT FROM $3)",
         )
-        .bind(&entry.namespace)
-        .bind(&entry.kind)
+        .bind(&entry.folder)
         .bind(&entry.name)
         .bind(params.user_id)
         .fetch_one(pool)
@@ -59,9 +58,7 @@ pub async fn run(
 
         if exists && !params.force {
             return Err(anyhow::anyhow!(
-                "Import aborted: conflict on [{}/{}/{}]",
-                entry.namespace,
-                entry.kind,
+                "Import aborted: conflict on '{}'",
                 entry.name
             ));
         }
@@ -81,9 +78,10 @@ pub async fn run(
         match add_run(
             pool,
             AddParams {
-                namespace: &entry.namespace,
-                kind: &entry.kind,
                 name: &entry.name,
+                folder: &entry.folder,
+                entry_type: &entry.entry_type,
+                notes: &entry.notes,
                 tags: &entry.tags,
                 meta_entries: &meta_entries,
                 secret_entries: &secret_entries,
@@ -98,8 +96,6 @@ pub async fn run(
             }
             Err(e) => {
                 tracing::error!(
-                    namespace = entry.namespace,
-                    kind = entry.kind,
                     name = entry.name,
                     error = %e,
                     "failed to import entry"