Add --enum-style const to CLI types and generate #2071

Tracks PR #2070.

Plan

Goal

Let appwrite types (TypeScript) and appwrite generate emit enum columns as an as const object plus a same-named union type, behind an opt-in --enum-style enum|const flag. enum is not erasable syntax: generated .ts files currently fail tsc --erasableSyntaxOnly (TS1294) and Node's type stripping refuses them (ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX). Default stays enum, so existing output does not change. Fixes appwrite/sdk-for-cli#277.

What changes (from the PR diff)

• templates/cli/internal/typegen/enum_style.go (new): EnumStyle type (enum, const), EnumStyleChoices(), ParseEnumStyle() which rejects unknown values.
• templates/cli/internal/typegen/typescript.go: shared TypeScript.DeclareEnum renderer with EnumStyle and Declaration options. For .d.ts, .d.mts and .d.cts destinations the const style emits export declare const X: { readonly ... }, because an ambient const can't take an object initializer (TS1254).
• templates/cli/internal/cmd/types.go: --enum-style flag. runTypes parses it, rejects const for non-TypeScript languages, and sets Declaration from the destination's extension.
• templates/cli/internal/cmd/generate.go, templates/cli/internal/generator/generator.go, templates/cli/internal/generator/typescript.go: --enum-style flag and Options.EnumStyle. generateEnums now uses typegen.TypeScript.DeclareEnum in place of its own enum printer.
• src/SDK/Language/CLI.php: copies the new enum_style.go and the three new golden files into the generated CLI.
• Tests: internal/typegen/language_test.go with goldens ts.const.appwrite.ts and ts.const.appwrite.d.ts; internal/generator/generator_test.go with golden server.const.types.ts; internal/cmd/typegen_commands_test.go covering the flag surface, the enum default, and rejection of unknown and non-TS values.

Remaining steps

1. Get review on feat(cli): add --enum-style const to types and generate #2070 and address any feedback. The PR is the whole code change.
2. Merge, then ship it in the next CLI release (regenerate appwrite/sdk-for-cli) and close TypeScript enums sdk-for-cli#277.
3. Mention --enum-style const in the CLI docs and changelog for types and generate.

Risks

• Default enum output has to stay byte-for-byte identical. The existing golden files guard this.
• A consumer switching to const may rely on enum-only behaviour such as reverse mapping or enum-typed declarations merging. The flag is opt-in, so only people who choose it are affected.

Done when

• feat(cli): add --enum-style const to types and generate #2070 merged with all checks green
• Default types and generate output unchanged against the existing goldens
• --enum-style const output passes tsc --strict --erasableSyntaxOnly for .ts and .d.ts destinations and for generate
• Released in a CLI version and TypeScript enums sdk-for-cli#277 closed