Persist prompt-cache telemetry after turns and use it to gate incremental
leaf compaction. Hot cache sessions now defer best-effort incremental
passes unless raw history pressure is clearly above target, while cold
cache sessions can run bounded catch-up passes in a single maintenance
cycle. Full threshold sweeps keep their existing behavior.

Also add cacheAwareCompaction config/schema support, docs, a changeset,
and regression coverage for hot/cold/unknown prompt-cache behavior.

Regeneration-Prompt: |
  Implement the cache-aware incremental compaction spec for lossless-claw
  using the new prompt-cache telemetry exposed by the dependent OpenClaw
  branch tied to openclaw/openclaw#62179. Persist lightweight per-
  conversation cache telemetry after each turn, classify sessions as hot,
  cold, or unknown, and use that state to decide whether afterTurn()
  should run incremental leaf compaction. Preserve the existing full-sweep
  compaction behavior, but let cold-cache sessions do a bounded number of
  extra leaf passes to catch up while hot-cache sessions defer passes
  unless raw history pressure is clearly above target. Add the minimal
  config surface for enabling the feature and setting the cold-cache pass
  cap, keep the plugin manifest and docs in sync, and cover the behavior
  with focused engine and config tests.

Add debug-level tracing around the new cache-aware incremental compaction and
dynamic leaf chunk sizing paths so live runs can be diagnosed without querying
SQLite directly. This logs telemetry updates, incremental decision inputs and
reasons, and leaf compaction start/result state, with focused engine coverage
for the new messages.

Regeneration-Prompt: |
  User asked for better observability for the two new incremental compaction
  features added on this branch: cache-aware prompt-cache handling and dynamic
  leaf chunk sizing. The requirement was to add debug logs, not info logs, and
  to explain how to enable those logs in a live OpenClaw instance.

  Inspect the new policy code in the LCM engine and add low-noise debug traces
  at the decision points that matter operationally: telemetry persistence after
  afterTurn, the incremental compaction decision with cache state / activity
  band / chosen chunk / reason / max passes, reset after a successful leaf
  compaction pass, and compactLeafAsync start/result. Preserve existing behavior
  and keep the logs structured enough to grep in production. Add focused tests
  that prove the debug logger is called for the hot-cache telemetry path, the
  hot-cache defer path, and the dynamic high-band chunk selection path.