feat: generate records from compile-time collections

TODO.md

@@ -41,6 +41,8 @@ initialized type-valued records/tuples support schemas/defaults, nested
 field/index updates and owned copies/captures inside compile-time producers.
 `field!` selects record/tuple/enum and sequence members using compile-time names,
 including runtime places and type-control updates without runtime reflection.
+`struct_type!` generates ordinary/C-layout records from constant name/type/default
+arrays or tuples, including loop-filled producer storage and owned defaults.
 general type-valued execution, metadata reflection and generic library acceptance remain open.
 the driver retains frontend storage and source provenance through
 `@source/compilation`, with compilation-wide AST node identities.
@@ -99,7 +101,8 @@ test discovery and FFI remain outside these completed slices.
   - [x] uninitialized value-array checkpoint: ordinary fixed arrays in type/type-array producers start with `undefined`, fill nested indices or replace whole arrays/rows, and generate storage/defaults through interpreter/native execution. owned snapshots preserve independent partial initialization in local copies; initialized scalar/string/optional/record/tagged-union elements retain exact types and ordinary checked operations. premature leaf reads and incomplete procedure arguments diagnose read-before-initialization. empty shapes, `.len` before initialization, mutability/type/index/bounds/overflow diagnostics, per-cell construction limits and repeatable compilation are verified. runtime undefined storage, uninitialized arrays in ordinary value-returning procedures, partial record construction and storage-bearing constant materialization remain open.
   - [x] type-record storage checkpoint: initialized records/tuples containing type values live inside type/type-array producers, including local schemas/defaults, typed/contextual/inferred construction, nested records/arrays, checked field/index reads and updates, whole-value replacement and immutable by-value collection captures. persistent snapshots isolate copies/captures while borrowed array places observe later updates; type leaves retain nominal identity and ordinary value leaves reuse checked IR. generated storage/defaults, invalid field/type/default diagnostics, readonly places, narrow overflow, imported producers/provenance, cached nominal results and repeatable compilation work through interpreter/native execution. field validation/construction shares the type-control bound. type-record procedure inputs/results are covered below; runtime type-valued records, partial record initialization, metadata reflection and inline expansion remain open.
   - [x] type-record procedure checkpoint: records/tuples containing type values cross compile-time procedure inputs/results, including nested arrays/records, aliases, defaults and dependent annotations. compile-time producers accept ordinary constant inputs; runtime generics accept erased `$` metadata parameters. owned snapshots isolate argument/result copies, exact type/value leaves retain checked diagnostics, and normalized cache keys preserve nominal generated types. generated storage/defaults, imported producers/provenance, shared execution bounds and repeatable compilation work through interpreter/native execution. runtime metadata storage, partial record initialization, reflection and inline expansion remain open.
-  - [ ] remaining gate: general type-valued compile-time execution, inline match/loop expansion and metadata reflection (`typeinfo!`, `struct_type!`, generated type/default arrays), broader constant materialization (including untagged unions and storage-bearing values), plus existing-library acceptance. required expression-valued control flow, compound updates, formatting parsing and imported C-binding support may interleave with later gates.
+  - [x] generated-record checkpoint: `struct_type!(layout, names, types, defaults)` builds ordinary records from constant fixed arrays or tuples with unique ASCII field names, concrete types and contextual optional defaults. literal heterogeneous collections, helper results and loop-filled producer arrays preserve exact types, owned defaults/copies and cached nominal identity through interpreter/native execution. `.auto` permits empty records; `.c` requires nonempty C-compatible fields and retains native field order/layout. malformed inputs, incomplete arrays, runtime dependencies, field/default validation, imported provenance, shared construction bounds and repeatable compilation retain diagnostics and isolation. metadata inspection, inline expansion, aggregate C calling conventions and storage-bearing defaults remain open.
+  - [ ] remaining gate: general type-valued compile-time execution, inline match/loop expansion and metadata reflection (`typeinfo!` and metadata collections), broader constant materialization (including untagged unions and storage-bearing values), plus existing-library acceptance. required expression-valued control flow, compound updates, formatting parsing and imported C-binding support may interleave with later gates.
 - [ ] remaining source constructs: expression-valued control flow and `yield`, compound updates and multiline strings. examples: `source/parser/parse.hon`, `source/llvm/runtime.hon`.
 - [ ] standard-library milestone: compile/run a multi-package program exercising existing allocation and IO, including error cleanup; no replacement miniature standard library.
 - [ ] native driver integration: required C ABI declarations, `process.Init` startup arguments/IO, actual CLI exit statuses, file loading, temporary files and spawning Clang. Honey-generated programs currently accept only parameterless `main` and print its result; Bro's bootstrap startup support is not Honey backend support.