fix: improved transaction handling

[aron23]

This pull request introduces FaceTheory support documentation and related planning to TableTheory, focusing on enabling correctness-first Incremental Static Regeneration (ISR) patterns using DynamoDB. It adds comprehensive guides, model schemas, and transaction recipes for cache metadata, lease/lock management, idempotency, and transactional updates, ensuring multi-language support (Go, TypeScript, Python). Additionally, the release version is bumped to 1.2.0, and the changelog is updated to reflect these and other recent changes.

FaceTheory ISR Enablement Documentation:

• Added a new roadmap (theorydb-facetheory-support-roadmap.md) outlining milestones for FaceTheory enablement, including canonical ISR lock helpers, transaction recipes, TTL cache patterns, and idempotency guidance.
• Introduced detailed guides for:
  • ISR cache schema and recommended DynamoDB item shapes, with runnable model definitions in Go, TypeScript, and Python (isr-cache-schema.md).
  • Transactional update patterns for safe metadata publishing and pointer swaps, including multi-language transaction examples (isr-transaction-recipes.md).
  • TTL cache patterns, operational guidance, and freshness vs expiry strategies (ttl-cache-patterns.md).
  • Idempotency patterns for request-driven regeneration, including lock and idempotency interplay (isr-idempotency.md).

Documentation and Planning Structure Updates:

• Updated documentation indexes (README.md and planning README.md) to reference new FaceTheory ISR guides and planning documents. [1] [2]

Release and Changelog:

• Bumped the project version to 1.2.0 and updated CHANGELOG.md to record new features, bug fixes, and FaceTheory documentation additions. [1] [2]