Address @tianyicui's minor-revision review on PR #110:
- Make every BasicCompactConfig knob required except `auto` (defaults
true): there is no data yet to justify default thresholds/budgets, so
a consumer states each value explicitly. Drop the DEFAULTS export and
the constructor's `= {}` default; example cordis.yml, the compaction
e2e, the README, and every test construction site now pass a complete
config (tests route through a `cfg()` helper).
- Add a TODO on estimateContentTokens: char/4 is coarse; replace with a
real tokenizer or post-response usage feedback in a follow-up.
- Add a TODO on the agent/pre-step `fullSystemPrompt` param flagging it
as a smell on a generic per-step seam (compaction is its sole
consumer); a `//` line comment so it stays out of the generated catalog.