docs: initial coding agent considerations for Copilot and Gemini

[Copilot]

Establishes lightweight guardrails for using AI coding agents (GitHub Copilot, Gemini Code Assist) in TCS Cloud Foundations workflows before ad-hoc adoption creates inconsistency or risk.

Added

• docs/coding-agents/considerations.md

  • Approved tools table with scoped use cases per tool
  • Core principles: mandatory human review, no secrets in prompts, license awareness, co-author attribution in commits
  • Copilot: IDE config, agent mode constraints (draft PRs only, no protected-branch write access), strong/weak use cases, provider-version watch-outs
  • Gemini Code Assist: organization license setup, PR review bot scope (suggestions only, does not satisfy branch protection), HCL version lag caveat
  • Data-handling constraint table — what can/cannot be passed to external APIs
  • Workflow diagram showing where agent-assisted work slots into the existing review cycle
  • Open questions checklist (agent mode trial, Gemini PR bot pilot, air-gapped model options)

• README.md — added reference to the new doc under "Current assets"