fix: address account valuation review findings

jarca_ledger_mcp/application/system_services.py

@@ -10,6 +10,8 @@ from .shared import (
     current_kst_month,
     datetime,
     db,
+    read_db,
+    read_operation,
     fail,
     hashlib,
     init_db,
@@ -29,6 +31,15 @@ def health_check(db_path: str | None = None) -> dict[str, Any]:
     return ok(server="jarca-ledger-mcp", db_path=path, schema_version=schema_version, active_transactions=tx_count)
 
 
+@read_operation
+def health_check_readonly(db_path: str | None = None) -> dict[str, Any]:
+    path = resolve_db_path(db_path)
+    with read_db(str(path)) as conn:
+        schema_version = conn.execute("SELECT value FROM schema_meta WHERE key='schema_version'").fetchone()[0]
+        tx_count = conn.execute("SELECT COUNT(*) FROM transactions WHERE status='active'").fetchone()[0]
+    return ok(server="jarca-ledger-mcp", db_path=path, schema_version=schema_version, active_transactions=tx_count)
+
+
 def _sha256_file(path: Path) -> str:
     digest = hashlib.sha256()
     with path.open("rb") as f:
@@ -186,8 +197,9 @@ def get_ledger_backup_status(file_path: str, include_hash: bool = True, include_
 
 from .accounts_write_services import create_ledger_account as create_ledger_account
 
+@read_operation
 def list_ledger_accounts(active_only: bool = True, db_path: str | None = None) -> dict[str, Any]:
     sql = "SELECT * FROM accounts" + (" WHERE active=1" if active_only else "") + " ORDER BY name"
-    with db(db_path) as conn:
+    with read_db(db_path) as conn:
         rows = conn.execute(sql).fetchall()
     return ok(accounts=[row_to_dict(r) for r in rows], count=len(rows))