feat(seed): year-as-int + conventional choice-set heuristics (#33, #34)

Two additive D7 catalogue rules, surfaced while writing the website seed
docs. No change to the type fallback, executor, or grammar.

#33 — year-like int columns. `published`/`birth_year` were just `int`, so
they fell to the unbounded int path and produced nonsense (`9419`). Add an
int-gated year rule (after the quantity rule, so `year_count` stays a
count): `year`/`*_year`/`published`/`founded` -> a bounded 1950-2025 year
(new `YearRecent`), or the dob-style birth window 1945-2007 for
`birth`/`born`/`dob` (new `YearBirth`). Plain int; not added to the D9
named-generator vocabulary.

#34 — conventional choice sets. A few enum-ish names have a near-canonical
small set that reads far better than lorem text. Add a type-gated PickFrom
lookup (reusing the existing generator): priority/prio, severity,
rating/stars. `status` is deliberately excluded (values too
domain-specific) and keeps the D12 advisory; a user IN-CHECK still wins.
`priority` leaves ENUM_TOKENS.

ADR-0048 Amendment 1; +8 tests (incl. a column-fill integration test that
also closes a pre-existing gap on that path).

docs/requirements.md

@@ -696,7 +696,10 @@ since ADR-0027.)
   `Generator`, and full completion / highlight / validity / help /
   parse-error-pedagogy wiring. Deferred SD2 increments:
   user-defined custom generators, NULL injection, multi-locale,
-  recursive parent auto-seed.)*
+  recursive parent auto-seed. Later catalogue refinements:
+  **#33** year-as-int (`year`/`*_year`/`published`/`founded`) and
+  **#34** conventional choice sets (`priority`/`severity`/`rating`,
+  `status` excluded) — ADR-0048 Amendment 1.)*
 
 ## Query analysis