fix(schema): preserve numeric and boolean enum types

[takiAA]

An int field tagged enum:"1,2" currently generates {"type":"integer","enum":["1","2"]}. The numeric values fail the enum constraint, while the string values fail the type constraint. Boolean and floating-point fields have the same problem.

Parse enum tags according to the generated field type so numeric and boolean values keep their JSON types. String enums remain strings, including values such as "true" and "1". Integer parsing preserves the full signed/unsigned 64-bit range; number enums use json.Number to avoid introducing float rounding. Unparseable tags keep their previous string representation.

The regression tests validate permitted and out-of-enum values through ParseAndValidate, cover a pointer to a named integer type, and check exact serialization of large integer enums. The validation and integer-serialization regressions fail on the unchanged code and pass with the fix.

Validation on Go 1.27.0, macOS arm64:

• go test ./... -count=1 -timeout=30m passed.
• go build ./..., gofumpt, and git diff --check passed.
• Both example modules build with a temporary -modfile and -mod=mod. Their checked-in module files report go: updates to go.mod needed on both the unchanged baseline and this branch; this PR changes no dependency files.
• golangci-lint v2.14.0 passed with 0 issues after merging the upstream fix from fix: stop matching GOAWAY by a deprecated type #415. The full test suite was rerun and passed on the updated branch.

Synced with main after #415 fixed the pre-existing http2.GoAwayError deprecation. GitHub Actions lint now passes.

• I have read CONTRIBUTING.md.
• New-feature discussion: not applicable (bug fix).