feat: comprehensive logging across parser, app, persistence, runtime (X1)

Completes the X1 full sweep started in a8ad0c6 (db.rs). Closes X1 -> [x].

- persistence/mod.rs: debug! on every yaml/CSV/history write -- the
  silent-failure-prone disk paths (write_schema, write_table_data incl.
  the empty->delete branch, append_history/_failure).
- runtime.rs: debug! on execute_command_typed dispatch (one per executed
  command, complements the db.rs executor logs).
- app.rs: debug! on submit (route + submission mode), dispatch_app_command,
  and the ADR-0044 diagram-vs-prose render-mode choice.
- dsl/parser.rs: trace! on parse begin/outcome at the parse_command_inner
  choke point -- trace, not debug, because the live overlay/completion
  re-parse per keystroke (hot path).
- logging.rs: documented level discipline (error/warn/info/debug/trace) so
  the convention survives across sessions.

Levels verified end-to-end through the real worker thread + logging::init.
~75 -> 135 tracing sites total. Tests: 2207 pass / 0 fail / 1 ignored.
Clippy clean.

src/runtime.rs

@@ -2531,6 +2531,7 @@ async fn execute_command_typed(
     command: Command,
     source: String,
 ) -> Result<CommandOutcome, DbError> {
+    debug!(verb = command.verb(), "execute command (routing to worker)");
     let src = Some(source);
     match command {
         Command::CreateTable {