Replace the bare-paren tuple grammar with explicit, position-unambiguous
forms, mirroring how structs work:
type `(A, B)` -> `Tuple(A, B)` (named keeps `:`)
value `(a, b)` -> `.(a, b)` (named uses `=`)
typed (new) -> `Tuple(A, B).(a, b)` (like `Point.{...}`)
failable `-> (T, !)` -> `-> T !`
`-> (T1, T2, !)`-> `-> Tuple(T1, T2) !` (channel outside Tuple)
Bare `(...)` is now grouping only, everywhere; a comma in bare parens is a
hard error with a migration hint. Grouping, function types `(A, B) -> R`,
param lists, lambdas, and match bindings are unaffected.
`Tuple(...)` is strictly a TYPE in every position (including `size_of` /
`type_info` args); a tuple VALUE comes only from `.(...)` (anonymous) or
`Tuple(...).(...)` (explicitly typed). A bare `Tuple(1, 2)` is a tuple
type with non-type elements -> rejected.
The ~110 tuple-bearing corpus files were migrated with a one-shot
AST-aware migrator (the `sx migrate` tool from the prior commit, removed
here). New examples: 0130 (new syntax), 0131 (typed construction), 1060
(named-tuple failable return). 1116 golden updated for the new hint text.
Pure source rename: all 97 'sqlite3_* ... #foreign sqlib "csym";' fn decls
→ 'extern sqlib "csym";' (+ the one stale header-comment reference). The
extern_lib axis references the 'sqlib' #import c unit identically to #foreign
sqlib, so IR/output is byte-identical. Empty snapshot diff; example 1624
(vendor-sqlite-module) stdout byte-unchanged. Suite green (647 corpus / 444
unit, 0 failed).
THREADSAFE=0 was correct when sx had no threads; with std.thread (S6)
and std.http's pooled dispatch (S7b), concurrent connections corrupted
sqlite's unprotected globals (caught live: distd under ab -c20 died
with free-of-unallocated inside yy_reduce). Serialized mode is
sqlite's own default and safe for every consumer; per-connection use
across threads is the supported pattern.
The vendored amalgamation (3.53.2, public domain) plus the curated
bindings move from the distribution repo into the sx library:
'#import "vendors/sqlite/sqlite.sx"' gives any sx program SQLite
with no system dependency and no build flags — the bindings declare
the C as a named #import c unit (pinned defines + -O2), compiled
through the object cache and shadow-proof via unit-first resolution.
examples/1624 pins the version and a typed round trip in-suite.
