feat: prepare configs for TypeScript 7

[bntvllnt]

Summary

• define the v2 compatibility contract for TypeScript 6.0.2 through 7.x and align the base preset with TypeScript 7 migration defaults
• validate all five shipped presets with both the TypeScript 6 compatibility compiler and the TypeScript 7 native compiler
• document direct TypeScript 7 adoption, the official side-by-side TS6/TS7 layout, and known consumer migration requirements
• install locked compiler dependencies in CI and release jobs with lifecycle scripts disabled and read-only quality-job permissions

Breaking changes for v2

• TypeScript 5 is no longer supported
• ambient type packages are opt-in through compilerOptions.types
• TypeScript 6 uses stableTypeOrdering to match TypeScript 7; the README records the upstream performance tradeoff

This PR prepares the package and its release checks; it does not publish v2 or change fleet consumers.

Verification

• npm ci --ignore-scripts
• npm test — 9 tests, including no-emit checks for every preset under TS6 and TS7
• npm publish --dry-run --json — prepublish tests pass and the expected 8-file package is produced
• isolated packed-package consumer — tsc6, tsc, and the TS6 JavaScript compiler API all pass
• npm audit --json — 0 vulnerabilities
• npm audit signatures — 4 verified registry signatures
• workflow YAML parse, diff whitespace, stale-doc, and secret-pattern checks

Closes #2

[greptile-apps]

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