fix(compiler): preserve immutable constant names in Rust - #6010

A valid immutable t27 constant such as type_documentation kept its public spelling but failed Rust -D warnings with non_upper_case_globals. Emit the allowance on that immutable value declaration only, preserving its exact API, type and value. Uppercase constants, mutable statics, type aliases, other backends and unrelated diagnostics remain unchanged.

Actual baseline: three controls pass and two naming regressions fail. Five strict Rust 1.96 tests pass after the fix, including 258 independent runtime values, caller-visible uppercase module state, a type-correct source value mutant that fails execution, and real unsigned-comparison and lowercase-mutable-static rejection controls. Full bootstrap: 2822 passed, zero failed, two ignored across 122 targets; corpus ratchet retains 95 expected failures and cap126.

Native audit of all 804 referenced sealed specs finds Rust-only changes in 25 specs/52 aliases. Actual RAW hashes match the seal path; only immutable declaration naming attributes change, with no new standalone diagnostic classes/counts. All old52 hashes matched the accepted baseline before native save/verify without force. Honest native reports remain 23 BLOCKED/2 PASS. Coverage stays 1449/1325/124 and the debt ledger is unchanged. A broader unpublished static version exposed old hanging/failing testbenches; those sources/seals are outside this change.

The stricter common-wrapper tri-net102 compile-only preview remains78 passing/zero regressions; integration_framework retains three unused-assignment warnings. This is not full corpus success or tri-net compiler PIN adoption. The branch is aligned to accepted repeat canonical d72b871 and uses its current native hook policy.

Closes #5994