Defer need-check-nil and clean up stale suppressions

emmylua deserialises an unknown diagnostic code to a catch all that
matches no checker, so every `invisible`, `nil-check` and
`global-element` suppression was silently doing nothing. Renamed to the
emmylua codes. `name-style-check` has no equivalent and is dropped, it
was already disabled under luals.

The `get_tile` suppressions referenced an api typedef bug from 2024
which no longer reproduces.

need-check-nil is deferred rather than disabled on merit: a third of the
407 findings come from MapPosition and BoundingBox being aliased as
`struct|[double, double]`, so every `entity.position.x` reads as
possibly nil. The rest need per site knowledge of runtime invariants.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.emmyrc.json

@@ -18,6 +18,7 @@
     },
     "$comment-disable": "Carried over from the luals config, which had these as editor only rather than checked in ci",
     "$comment-unnecessary-if": "Disabled by the config fmtk generates for itself, the api union types make it unreliable",
+    "$comment-need-check-nil": "To be enabled once the backlog is cleared, a third of it is MapPosition and BoundingBox being aliased as struct|[double, double]",
     "diagnostics": {
         "globals": [ "__DebugAdapter", "__Profiler" ],
         "disable": [
@@ -26,6 +27,7 @@
             "invert-if",
             "missing-parameter",
             "missing-return-value",
+            "need-check-nil",
             "param-type-mismatch",
             "preferred-local-alias",
             "redefined-local",