Continue fold-2: migrate the global-value read/store/addr-of family (non-tagged)
from bespoke build+run C twins to test/lang @test, retiring each twin in the
same commit. Runtime coverage MOVES from $(TESTS) to test-lang (T1 runs+asserts
via `ww test`) + test-lang-byteid (T2 keeps cs==ww .s byte-id); the $(TESTS)
headline drops 3 (421->418). All asserts are primitive int comparisons; fresh
globals are zeroed, so a store that misses the symbol reads back 0 and FAILS.
989_globptrfield_run.c -> glob_ptr_field_test.ww (scalar field store through a module-global *struct pointer loads the pointer from gp(SB), not saved BP; runtime gp=&backing form, static-init is #48-blocked)
989_globstructret_run.c -> glob_struct_ret_test.ww (returning a module-global struct ident by value copies g's bytes; rsz 16 + rsz 24, each field asserted)
989_dotbasehijack_run.c -> dotbase_hijack_test.ww (indexing an [N]T field of a module-global struct addresses the struct field, not an unrelated global sharing the field name; +typed-inner control +colliding-global-intact pin)
glob_ptr_field keeps only the .c's offset-0 row: an added non-zero-offset row
(gp.g=9) surfaced a cs!=ww divergence (cstage folds the offset into the store
displacement `MOVQ AX,8(BX)`; wwstage emits `ADDQ $8,BX; MOVQ AX,(BX)`) — a
latent global-*struct-pointer field-store divergence beyond the .c's coverage,
reported for the backlog, not carried here. Bump LANGBYTEID_EXPECTED_MIN 35->38.