chore(deps-major): migrate typescript to 6.0.3 2026-06-29

[ericmaster]

This pull request migrates the project to TypeScript 6.0.3, Zod 4, and updates @types/node alongside it.

This introduces a few explicit fixes to adapt to the breaking changes from the major version bumps:

1. z.record() now requires an explicit key type; updated z.record(z.any()) to z.record(z.string(), z.any()).
2. TypeScript 6.0 tightened overlap validations for interface widening. Type assertions when reading env properties iteratively using dynamic keys are adjusted using an unknown cast (env as unknown as DynamicEnv).
3. An obsolete @ts-expect-error over Llama model string identifiers has been removed.
4. Resolved a typing inheritance mismatch for RESEND_DOMAIN_KEYS between worker-configuration.d.ts and workers/types.ts.
5. Suppressed TS6 baseUrl deprecation diagnostics for the bundler-based workflow where we currently utilize project references and TS 6 verbatimModuleSyntax.

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PR created automatically by Jules for task 16253482569276034942 started by @ericmaster

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