Feedback uploads are trimmed client-side to an 8 MiB budget

Before a bug report is submitted, Claude Code measures the payload and, if it exceeds 8388608 bytes (with a 65536-byte safety margin), trims it: oldest transcript messages are dropped first, individually oversized messages are removed, and the raw session log tail is shortened or dropped entirely. A machine-readable note describing what was trimmed is appended to the report description, and if the payload is still over budget afterward, an error-level log is written. The feedback_draft_submit failure event also gained a from_this_session field.