Harden summarize_session to chunk + merge long sessions (imported convos can
exceed the local model's context), and add summarize_all: idempotent, resumable
batch that summarizes every session needing it (skips up-to-date ones), with
progress logged to the live log. `lyra-summarize [limit]` CLI.
This is the first consolidation stage feeding the profile (semantic memory) and
era-rollup tiers.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>