Improve PR and Issue template

[eskenazit]

Add fields for the gent context to help them fill-in

example :

agent_name: "ADR → Feature Request"
tool: "Notion + GitHub"
llm_model: "Claude Sonnet 4.6"
confidence: "medium"
source_event: "user request"
source page "ADR: Cross-Adapter Factorization: Domain-Driven Core"