chore: sync ai prompts and oxlint config

[jan-kubica]

Summary

• add the shared ai-shared submodule and generated AGENTS/CLAUDE/GEMINI guidance
• adopt @stll/oxlint-config and update oxlint scripts
• fix the lint issues surfaced by the shared config

Checks

• bun run lint
• bun run typecheck
• bun run format:check
• bun run sync-ai:check
• bun test test/invariants.test.ts test/properties.test.ts test/generate.test.ts test/mutations.test.ts test/parse.test.ts

[gemini-code-assist]

Code Review

This pull request updates the project's development guidelines, AI agent skills, and linting configuration. It replaces the static oxlint.json with a dynamic oxlint.config.ts using @stll/oxlint-config, updates package.json scripts, and adds an auto-generated AGENTS.md file for AI context. Additionally, it refactors various TypeScript files and tests to improve type safety (using helper guards like isRecord and isValidator instead of unsafe type assertions), replaces array lookups with Set.has(), avoids spread operators on strings/arrays, and adopts .at() for safer string indexing. There are no review comments, so I have no feedback to provide.

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[chatgpt-codex-connector]

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