fix: preserve RCA context in bug Q&A

[eshulman2]

Root cause

The shared answer_question node is annotated with FeatureState. LangGraph uses node input annotations to filter state channels, and FeatureState does not define the bug-only rca_content or rca_options fields. Consequently, the compiled bug workflow removed both fields before invoking Q&A, producing a prompt with a blank RCA section even though the RCA had been generated and displayed at the preceding gate.

Direct qa_handler unit tests did not expose this because they called the function without compiling it into a LangGraph state graph.

Fix

• register a BugState-typed Q&A wrapper in the bug graph so generated RCA content and fix options reach the shared handler
• add a compiled-graph regression test that proves both fields survive LangGraph input filtering
• include Jira summary and description in the generic Q&A prompt
• fall back to the ticket description when artifact generation context has no raw requirements

Testing

• 173 focused tests passed
• Ruff passed