gen.c: implement floats

[serkonda7]

No description provided.

[Copilot]

Pull request overview

This PR adds float support to the C backend by wiring floats through the type system, checker, code generator, builtins, tests, and CI. It fits into the compiler/runtime codebase by extending existing numeric handling so float literals and mixed numeric expressions can compile and run under the C backend.

Changes:

• Add f32/f64 builtin/runtime support and register them as numeric types.
• Implement C code generation for float literals and allow numeric promotion from ints/f32 to float targets.
• Add float tests, enable C float tests in CI, and update docs/changelog to describe float support.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/float/promotion_test.bt	Adds coverage for mixed float/int promotion and += behavior.
tests/float/float_test.bt	Keeps basic float literal test file aligned with current header format.
lib/builtin/number.js.bt	Adds JS-side f32/f64 conversion helpers for numeric consistency.
lib/builtin/number.c.bt	Introduces C float type aliases and float str() implementations.
lib/bait/gen/c/expr.bt	Replaces the float-literal panic with actual C emission support.
lib/bait/checker/type.bt	Expands implicit promotion rules to include float targets.
lib/bait/ast/types.bt	Marks f32/f64 as numeric builtins and adds signed/unsigned helpers.
docs/docs.md	Updates language docs to describe float types and promotion rules.
CHANGELOG.md	Records float implementation under C backend changes.
.github/workflows/ci.yml	Enables the C backend float test suite in CI.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.