Resolves issue 0090. The `{}` integer formatter mis-rendered both ends of
the 64-bit range:
- `int_to_string` computed the magnitude as `0 - n`, which overflows for
`s64::MIN` (its magnitude is unrepresentable as a positive s64) — the
value stayed negative, the digit loop ran zero times, so only `-`
printed. It now extracts digits straight from `n` (per-digit
`|n % 10|`, `n` truncating toward zero), never negating MIN.
- `any_to_string`'s `case int:` formatted every integer as s64, so a u64
all-ones value printed as `-1`. There was no `uint` type-category to
distinguish signedness. Added an additive `type_is_unsigned(T)`
reflection builtin (static fold + dynamic interp/LLVM paths, mirroring
`type_name`), backed by the new `TypeTable.isUnsignedInt` predicate, and
a `uint_to_string` formatter (unsigned decimal via long-division over
four 16-bit limbs). `case int:` routes through `type_is_unsigned(type)`.
The 16-bit-limb split is factored into a shared `decompose_u16x4`, now
reused by `int_to_hex_string` (no second unsigned-math routine).
Regression: examples/0046-basic-int-formatter-extremes pins both extremes
plus a width spread; unit tests cover `isUnsignedInt`. Docs (specs.md
representation note, readme std API) updated for unsigned/extreme `{}`
behavior. IR snapshots refreshed for the two new std functions.
Test-first scaffolding ahead of extracting src/ir/conversions.zig — no code
change to the coercion targets (lowerXX / coerceToType / coerceOrErase /
buildProtocolErasure / tryUserConversion / failable-adapter selection).
Adds 4 .ir snapshots (first .ir for 01xx/09xx/10xx), each captured surgically
via `sx ir | normalize_ir`, path-free, idempotent, and print-free at IR-gen time
(0114-types-build-block-convert was rejected — it prints `--- void / 0 args ---`
+ sx source at IR-gen):
- 0107-types-int-cmp-in-float-ternary numeric int<->float coercion
- 0903-optionals-optional-roundtrip optional wrap/unwrap
- 0904-optionals-any-to-string-optional xx unbox_any + optional
- 1004-errors-try error-channel adapter/coercion
Protocol erasure + user Into are already pinned by the 04xx snapshots
(0400/0413/0414/0416); duplicate-conversion rejection by the 0410/0411/0412
anchors.
Adds 1 unit test via the public surface (no new exposure, mirroring A4.1/A4.2
sub-step 1): optionalOfFlattened — the optional wrap/flatten coercion rule
(T -> ?T; ?T -> ?T, never ??T; contrasted with the non-flattening optionalOf).
The lowerXX/coerceToType/coerceOrErase/buildProtocolErasure decisions are private
+ emission-bound, so their CoercionPlan unit tests land with the extracted module
in sub-step 2.
zig build, zig build test, tests/run_examples.sh (357/0) all green.
