fix: handle missing scrip column in April 2026 KSEI PDF

The April 2026 IDX ownership PDF omits the zero-valued scrip column for
some holders, causing the parser to leave holdings_scripless/scrip as
empty strings. This broke normalize_ksei_row which called parse_id_number
on empty input.

Two-layer fix:
- Parser: pop_numeric_tail handles 2-column (missing scrip) rows by
  defaulting scrip to "0"
- Normalizer: parse_id_number_or_zero backstop treats empty component
  share fields as 0 while still requiring total_shares

Also includes AGENTS.md refresh, formatting cleanup (rustfmt), and
version bump to 0.2.2.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/main.rs

@@ -78,16 +78,14 @@ fn run() -> Result<(), IdxError> {
         }
         Commands::Stocks(stocks) => {
             let provider = default_provider(config.provider, cli.verbose > 0);
-            if let Err(err) =
-                cli::stocks::handle(
-                    stocks,
-                    &config,
-                    &provider,
-                    cli.offline,
-                    cli.no_cache,
-                    cli.verbose > 0,
-                )
-            {
+            if let Err(err) = cli::stocks::handle(
+                stocks,
+                &config,
+                &provider,
+                cli.offline,
+                cli.no_cache,
+                cli.verbose > 0,
+            ) {
                 emit_error(&err, &config.output);
                 return Err(err);
             }