build: migrate to TypeScript 7.0

[nazarhussain]

Summary

Migrates the toolchain from the tsgo native-preview to the TypeScript 7.0 RC, which ships the native (Go) compiler as the standard typescript package with the standard tsc binary (no more tsgo).

Changes

• Replace @typescript/native-preview + typescript@6 with typescript@7.0.2.
• Add @typescript/typescript6 (exposes the tsc6 binary) for side-by-side TS6 fallback/comparison during the RC period.
• Convert all tsgo → tsc in build / build:watch / check-types scripts across every package.
• Refresh workaround comments that referenced the native compiler (import-elision #2212, StrictEventEmitter overload cast).

Verification

• pnpm check-types passes across all 17 workspace packages (exit 0, no type errors).
• pnpm install --frozen-lockfile passes — lockfile is in sync.
• No remaining tsgo / @typescript/native-preview references in the repo.
• tsconfig.common.json was already compatible with TS7 (explicit target: es2023, module/moduleResolution: nodenext, explicit strict and types, no baseUrl) — no config changes needed.

Notes

• tsc6 is installed but not yet wired into any script — kept for manual TS6↔TS7 comparison compatibility issues if encountered.

AI disclosure

Reviewed and committed with assistance from Claude Code.

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request replaces the tsgo compiler tool with the standard TypeScript compiler (tsc) across all packages, updating the build and type-checking scripts accordingly. Additionally, it upgrades the main typescript dependency to 7.0.1-rc and introduces @typescript/typescript6 to replace @typescript/native-preview. Comments referencing tsgo workarounds have also been updated to reference tsc. There are no review comments to address, and I have no additional feedback to provide.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Keep TypeScript API consumers on the TS6 alias

When any existing ts-node-based script runs (for example each package's check-readme calls scripts/check_readme.ts, which imports typescript and uses createProgram), Node now resolves that import to typescript@7.0.2. TypeScript 7.0 only provides the native CLI and does not ship the stable compiler API that ts-node and check_readme.ts need; the TS6 API is installed as @typescript/typescript6, but tools that import the peer name typescript will never see it. This makes docs/readme/spec-download scripts fail even though tsc itself works; alias typescript to @typescript/typescript6 and install the TS7 package under a separate alias for its tsc binary.

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