feat(storage): migration v6 — profiles + profile_terms + Default-guard triggers; seed from dictionary

crates/storage/src/lib.rs

@@ -2,6 +2,10 @@ pub mod database;
 pub mod file_storage;
 pub mod migrations;
 
+/// Stable identifier for the seeded Default profile (see migration v6).
+/// The Default profile cannot be renamed or deleted — guarded by SQLite triggers.
+pub const DEFAULT_PROFILE_ID: &str = "00000000-0000-0000-0000-000000000001";
+
 pub use database::{
     add_dictionary_entry, complete_subtask_and_check_parent, complete_task, count_transcripts,
     delete_dictionary_entry, delete_task, delete_transcript, get_setting, get_task_by_id, uncomplete_task,