own: lazy fills through @nodrops C calls, stores then used, a let given fresh values on some paths (TSLANG 63-66) - #854

More gaps found by compiling powder_sandbox's native_ts_graphics under -mm=own (TSLANG_ISSUES 63-66).

• 63: a lazy getter that fills an empty field through a @nodrops C call (core/nri.ts's cachedVertexBuffer getters). A C declaration with no export, import or dllimport, not variadic, and given and returning only numbers, strings, null/undefined or @cpp handles, runs nothing of the module, so the fill (TSLANG 47) holds across it.
• 64: a value moved into a field of an object already pushed into an array, then used (simple_pbr_nri.ts). This includes a new in one arm of a ?:.
• 65: a value moved into an element, or a local's value moved into a field or an element, then used (logic_op_dynamic_state_nri.ts). It borrows the element or field from the store on, as TSLANG 50 does.
• 66: a let borrowing a field, then given a fresh value on some paths (core/donut_first_person_camera.ts's animate). After a failed dry run, each fresh value goes into a slot of its own, released where the let is, and the let borrows it. Escapes, a field overwritten before the use, and loops are checked like any other borrow. own_err_field_let_assigned now uses a shape that is still refused (the let changed in place through its slot); its old shape compiles and runs correctly.

Sweep of the 276 ntg sources: 807 → 664 errors and 119 → 118 failing, with no source getting more errors. The camera module now compiles, and with its facts so do the calls into it.

Tests: 00tslang_issue_63.ts and 00tslang_issue_66.ts (every model), plus own_err_local_stored_element_reset, own_err_pushed_object_field_popped, own_err_split_let_stored and own_err_split_let_field_overwritten.

Validation: full ctest (Release) passed 7303/7304; the one failure was the outdated own_err_field_let_assigned expectation, which is fixed here and passes. DefaultLib tests.ps1 passes on all four models (see comment).

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