Add a Claude SessionEnd memory adapter

[janitor-manager]

Parent: #7

Add the Claude-native adapter after its transcript records have a stable, safely filterable contract.

Current blocker: SessionEnd supplies transcript_path, but the hook contract does not fully define the JSONL record schema needed to prove exclusion of tool payloads, secrets, and non-conversation records.

Acceptance:

• Bind only to the documented Claude SessionEnd input contract.
• Parse a stable documented/exported conversation schema.
• Require explicit enablement and agent_id.
• Filter non-conversation/tool/credential material, then call the retry-safe session ingest API.
• Add deterministic fixtures and installation/disable/failure documentation.