Fix review findings: validate the hooks cap, integer read caps, doc drift, config plumb-through test

A Codex review pass on the draft caught four real gaps and two solid
suggestions; all addressed except one pushed back on the merits:

- hooks-claude/hooks-codex: stderrSummaryMaxChars was the one new knob
  with NO range validation — a negative/NaN cap would silently
  misbehave inside slice(). Both bridges now assert a positive integer
  at the TOP of apply() (before the config-file parse's early return,
  so a bad value fails the load loudly), with rejection tests.
- tool-fs: the read caps count lines/chars/bytes, so positive-FINITE
  was too loose (a fractional readLimit would flow into windowing
  arithmetic and the schema description). All four now require a
  positive integer, matching tool-web's cap.
- Doc drift the gates cannot catch: tool-web's README tools table
  still named WEB_SEARCH_MAX_RESULTS as the mechanism; compact-basic's
  README/module doc and the compaction-capability-seam RFC still
  described estimation as fixed char/4 rather than the charsPerToken
  default.
- subagent-acp: the dispose graces were tested only at the
  startAcpRun level, so a regression that stopped threading plugin
  config into AcpRunSpec would have survived. A provider-path test now
  drives the trap-escalation scenario through ctx.subagents.start with
  small config graces and bounds dispose at 4s.

Pushed back on: converting compact-basic's charsPerToken to a
schemastery field. The package's whole config is deliberately
hand-rolled (resolveConfig, every threshold REQUIRED with no default —
a documented design posture); one schemastery field beside it would be
incoherent. The knob is cordis.yml-reachable, defaulted, and validated,
which is what the convention requires; migrating the package to
schemastery wholesale is pre-existing config-surface hygiene out of
this change's scope.

packages/compact/compact-basic/src/index.ts

@@ -2,7 +2,8 @@
  * `BasicCompactService`: the first implementation of the
  * `@deepseek-ai/dsh-compact` seam. It owns the entire compaction strategy:
  *
- * - **Token estimation** — char/4 heuristic with per-block structural overhead.
+ * - **Token estimation** — chars/`charsPerToken` heuristic (config, default 4)
+ *   with per-block structural overhead.
  * - **Retention policy** — walk surface nodes tail→head, keep recent nodes up
  *   to a token budget, compact everything older. The cutoff is snapped forward
  *   to the next balanced tool-pairing boundary so a compacted region never