Add .github/copilot-instructions.md for Copilot cloud agent onboarding

[Copilot]

Adds .github/copilot-instructions.md so the Copilot cloud agent can orient itself to this repo without exploratory overhead.

Contents

• Architecture — role of ModelParser / Validator / Loader / utils, instantiation signatures, and key method inventory
• TSV conventions — type column, guid field, relationship column pattern (<node>.<key_prop>), ; delimiter for list-type and multi-parent fields, subgraph column semantics
• MDF / bento-mdf — model YAML pair structure, pinned bento-mdf==0.13.1, runtime model download via libs/prefect-toolkit
• Prefect workflows — all seven deployed flows, submodule-clone-at-runtime pattern, work pool, dual logging (Prefect UI + S3-uploaded log file)
• AWS — Secrets Manager for DB credentials, S3 for data in/out, LocalStack support via LOCALSTACK_ENDPOINT_URL
• Testing — unittest + pytest from repo root, mock patterns, conditions under which tests skip
• Known pitfalls — submodule not initialized, fragile relative sys.path injection in workflow files, bento-mdf version lock, no installed package (src is always path-injected)

[qiongL910]

lgtm

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

[svburke]

LGTM