fix(toolchain): document TypeScript support ceiling

[mrnicholasbcarter-code]

Summary

• Resolve issue Establish TypeScript 7 compatibility with ts-jest or pin the supported toolchain #14 by making the supported TypeScript/ts-jest boundary explicit.
• Pin TypeScript to the tested 5.9.x line because ts-jest 29.4.x declares typescript >=4.3 <7.
• Add CI/publish assertions so unsupported compiler upgrades fail clearly rather than through npm peer-resolution surprises.
• Repair the clean-consumer package smoke to use the current @verdict/node package boundary while preserving the existing public API exports.
• Update the rebrand documentation and remove the stale core test-count claim.

Fixes #14

Evidence

• npm ci passed.
• npm run typecheck passed.
• npm run build passed.
• npm test -- --runInBand: 139 tests passed.
• npm run format:check passed.
• npm run verify:package passed: 16 shipped files, clean ESM imports, and TypeScript declarations.
• Context7 official ts-jest docs confirm the current peer range typescript >=4.3 <7.
• Code Review Graph updated and exact diff analyzed; remaining DeepObjectValidator gap is pre-existing validator coverage outside this bounded toolchain/doc change.

[mrnicholasbcarter-code]

Independent exact-diff review completed: official ts-jest documentation confirms ; the PR makes the supported 5.9.x ceiling explicit, repairs the package smoke boundary, and all required checks are green. Self-approval is unavailable for the PR author.