feat: update ParametersTypeCoder and ParameterExportTypeCoder to emit output under version subdirectories

[Copilot]

Summary

ParametersTypeCoder and ParameterExportTypeCoder were not following the types/<version>/... output convention already used by SchemaTypeCoder and ResponseTypeCoder. This change brings them into alignment so all type coders (except OperationTypeCoder) isolate per-version output under types/<version>/.

ParametersTypeCoder.modulePath()

• Before: parameters/<path>.types.ts (no types/ prefix, wrong subdirectory)
• After: types/<version>/paths/<path>.parameters.ts when versioned, types/paths/<path>.parameters.ts when not

ParameterExportTypeCoder.modulePath()

• Removed the public _modulePath!: string field that was set post-construction by callers
• modulePath() now computes the path directly from this.version and this.requirement.url, identical logic to VersionedArgTypeCoder

OperationTypeCoder cleanup

• Removed the now-unused modulePath parameter from exportParameterType() and buildDollarArgType(), and the coder._modulePath = modulePath assignment

Tests

• Updated existing ParametersTypeCoder modulePath test to expect the new path format
• Added versioned and empty-version modulePath tests for ParametersTypeCoder
• New test file test/typescript-generator/parameter-export-type-coder.test.ts covering versioned and non-versioned modulePath() behaviour

Original Prompt

SchemaTypeCoder and ResponseTypeCoder already emit their output under types/<version>/... when a non-empty version is set. The remaining TypeCoder subclasses that produce version-specific type files must be updated to follow the same convention.

Context

The multi-version code generation strategy is:

Every TypeCoder except OperationTypeCoder writes its output into a types/<version>/ subdirectory when a version is present, so that the types for each version are fully isolated. OperationTypeCoder is the exception: it lives at the shared path and imports/merges types from all version subdirectories (see companion issue).

SchemaTypeCoder and ResponseTypeCoder already implement this:

types/v1/components/MySchema.ts
types/v1/responses/MyResponse.ts
types/v2/components/MySchema.ts
types/v2/responses/MyResponse.ts

The following coders still need to be updated:

• ParametersTypeCoder – emits types/paths/<path>.parameters.ts
• ResponsesTypeCoder – emits types for the combined response object
• ParameterExportTypeCoder – emits individual exported parameter types

Proposed change

For each coder listed above, update modulePath() to insert the version segment between types/ and the remainder of the path when this.version is non-empty, mirroring the pattern already used in SchemaTypeCoder and ResponseTypeCoder:

// before
return `types/paths/${pathString}.parameters.ts`;

// after
return pathJoin("types", this.version, "paths", `${pathString}.parameters.ts`);
// → "types/v1/paths/pets.parameters.ts" when version = "v1"
// → "types/paths/pets.parameters.ts"    when version = ""

No other behaviour should change; only the output file location is affected.

Acceptance criteria

• ParametersTypeCoder.modulePath() returns types/<version>/paths/... when version is non-empty and types/paths/... when empty
• ResponsesTypeCoder.modulePath() (if it declares one) follows the same convention
• ParameterExportTypeCoder.modulePath() follows the same convention
• Existing unit tests for modulePath() on each affected coder continue to pass
• New unit tests assert the versioned path for a non-empty version on each affected coder
• Single-spec (no version) generation produces identical output to today

Manual acceptance tests

• Single-spec (no version) generates parameter type files at types/paths/<path>.parameters.ts with no version segment inserted
• Multi-version spec (e.g. version: "v1") generates parameter type files at types/v1/paths/<path>.parameters.ts
• ParameterExportTypeCoder exports (e.g. HTTP_GET_$_Query) land in types/v1/paths/<path>.types.ts when version = "v1" and types/paths/<path>.types.ts when version = ""
• Routes without a version continue to work as before with no generated-output changes
• TypeScript compilation of generated output succeeds for both versioned and non-versioned specs

Tasks

• Updated ParametersTypeCoder.modulePath() to use pathJoin("types", this.version, "paths", pathString) + ".parameters.ts"
• Replaced ParameterExportTypeCoder._modulePath field with a self-contained modulePath() that computes the versioned path from this.version and this.requirement.url
• Removed now-unused modulePath parameter from OperationTypeCoder.exportParameterType() and buildDollarArgType() (and their call sites)
• Updated existing ParametersTypeCoder modulePath test; added versioned and empty-version assertions
• Created test/typescript-generator/parameter-export-type-coder.test.ts with non-versioned, versioned, and empty-version modulePath tests
• Added patch-level changeset