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.
