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/hooks/hooks-codex/tests/coverage.spec.ts

@@ -207,6 +207,16 @@ describe('hooks-codex coverage — decision mapping paths', () => {
     expect(res?.type === 'hook/result' && res.data.stderrSummary?.length).toBe(501) // default 500-char cap + ellipsis
   })
 
+  it('rejects a non-positive or fractional stderrSummaryMaxChars at load', async () => {
+    const d = dir()
+    hooks(d, {})
+    for (const bad of [0, -5, 1.5, Number.NaN]) {
+      const adapter = new MockAdapter([])
+      await expect(harness(join(d, 'hooks.json'), adapter, { stderrSummaryMaxChars: bad }))
+        .rejects.toThrow(/hooks-codex: stderrSummaryMaxChars must be a positive integer/)
+    }
+  })
+
   it('the stderr summary cap is plugin config (stderrSummaryMaxChars)', async () => {
     const d = dir()
     hooks(d, { PreToolUse: [{ hooks: [{ type: 'command', command: sh(d, 'l.sh', '#!/usr/bin/env bash\nprintf "x%.0s" {1..600} >&2\nexit 2\n') }] }] })