fix: preserve JavaScript numbers in numeric enums

[proggeramlug]

Numeric enums stored values as i64, so fractional initializers such as 1.5 became incorrect integers. Keep numbers as f64 through constant evaluation, HIR, enum images, and constant emission. Reverse mappings use JavaScript number formatting for fractions, large values, NaN, and infinities.

Computed initializers evaluate once in declaration order, and reverse mappings consume the forward assignment result, including when an inherited setter intercepts the store. TS constant -0 emits +0 like tsc, while dependent constant expressions retain its sign during evaluation and computed members preserve runtime negative zero.

Validation:

• HIR enum tests: 25 passed; codegen enum tests: 3 passed; number emission tests: 4 passed.
• Fractional/large/non-finite, const-enum, merged-enum, keys, signed-zero, and computed-setter fixtures match unmodified TypeScript 5.8.2 transpilation executed by Node 26.8.1.
• Controlled tscwork A/B on qb8: medians 12,174,515,045 → 12,174,526,168 instructions:u (n=3, +0.000091%, within run variance). Both link the same runtime; linked .text is byte-identical at 59,780,386 bytes. Baseline is main 44874ef with build metadata aligned to 0.5.1661 (790ac7562), compared with compiler 81a0ae7.
• Final pmcheck.sh enf -p perry-hir -p perry-codegen --lib enum passed at c1f7f40 after rebasing onto the module-identity and class-family changes: build, sidecars, zod/tsc smoke, and 25 HIR + 3 codegen enum tests. Both enum fixtures also match Node in fast and auto-optimized modes on that compiler.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 05cfd2d and c1f7f40.

⛔ Files ignored due to path filters: 1

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing: 37

• CLAUDE.md
• Cargo.toml
• changelog.d/12788-numeric-enum-numbers.md
• crates/perry-codegen-js/src/emit/decls.rs
• crates/perry-codegen-wasm/src/emit/string_collection.rs
• crates/perry-codegen/src/expr/bigint_set.rs
• crates/perry-codegen/src/expr/literal_descriptor.rs
• crates/perry-codegen/src/type_analysis_facts.rs
• crates/perry-hir/Cargo.toml
• crates/perry-hir/src/analysis/value_types.rs
• crates/perry-hir/src/analysis/value_types_tests.rs
• crates/perry-hir/src/enums.rs
• crates/perry-hir/src/ir/decl.rs
• crates/perry-hir/src/lib.rs
• crates/perry-hir/src/lower/const_fold_fn.rs
• crates/perry-hir/src/lower/context_new.rs
• crates/perry-hir/src/lower/enum_image.rs
• crates/perry-hir/src/lower/enum_image/tests.rs
• crates/perry-hir/src/lower/expr_member.rs
• crates/perry-hir/src/lower/expr_object.rs
• crates/perry-hir/src/lower/lower_expr/arm_ident.rs
• crates/perry-hir/src/lower/lowering_context.rs
• crates/perry-hir/src/lower/module_decl.rs
• crates/perry-hir/src/lower/module_decl/namespace.rs
• crates/perry-hir/src/lower/module_decl/typescript.rs
• crates/perry-hir/src/lower/stmt.rs
• crates/perry-hir/src/lower/tests.rs
• crates/perry-hir/src/lower_decl/body_stmt.rs
• crates/perry-hir/src/lower_decl/enum_decl.rs
• crates/perry-hir/src/number.rs
• crates/perry-hir/src/stable_hash/decls.rs
• crates/perry-hir/src/stable_hash/expr.rs
• crates/perry-hir/src/stable_hash/primitives.rs
• crates/perry-hir/src/stable_hash/tests.rs
• crates/perry-wpfacts/src/gen_expr.rs
• test-files/test_gap_enum_computed_setter.ts
• test-files/test_gap_enum_fractional.ts

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