fix(planner): gracefully handle LLM structural hallucinations and add…

[Bala-Vignesh-S-M]

… rule for answer node

Capability

What can a user do after this change that they could not do before?

Proof

• I added one evidence subsection to README.md.
• It contains the exact prompt or API request.
• It contains the graph and ordered event trace.
• It contains the actual final result and evidence.
• It identifies every agent/provider assignment.
• It shows an adversarial failure before the fix and the same attack failing afterward.
• It includes commands that reproduce the result from a fresh checkout.

Boundaries

• glc_v3 still owns all provider credentials and model routing.
• Memory authorization happens before retrieval.
• No .env, credentials, personal memory, databases, or unrestricted local paths are committed.
• uv run ruff check . passes.
• uv run pytest -q passes.