Expose audited hardcoded tunables as plugin config

The audit swept every packages/*/* plugin for the new AGENTS.md
convention (no hardcoded tunables in plugins) and exposes each finding
as a defaulted, validated Config field. Defaults are the previously
hardcoded values throughout, so no deployment or golden changes.

- tool-fs (had NO Config): readLimit, readMaxLineLength, readMaxBytes,
  readStreamMinSize. The caps thread through ReadToolCaps/ReadWindow —
  read-render already documented that the consumer applies the caps, so
  they become explicit per-request fields.
- tool-web: searchMaxResults (WEB_SEARCH_MAX_RESULTS stays as the
  schemastery default). Also fixes the stale GREP_LIMIT references in
  search.ts and the web-capability-seam RFC (no such constant exists).
- bash-local: graceMs (SIGTERM->SIGKILL escalation grace). The
  RunInternals.graceMs test seam is gone: graceMs is now a required
  SpawnSpec field filled from config, so tests exercise the real
  config path and the defaults live in exactly one place.
- subagent-acp: disposeEofGraceMs / disposeGraceMs. The AcpRunSpec
  fields become required for the same one-defaulting-layer reason.
- session-persistence-sqlite: journalMode ('wal' default; the
  rollback-journal modes serve filesystems where WAL's shared-memory
  files do not work, e.g. network mounts).
- hooks-claude + hooks-codex: stderrSummaryMaxChars for the persisted
  hook/result stderr summary. The duplicated summarize() helpers merge
  into hook-protocol's summarizeStderr(stderr, maxChars), beside the
  HookResultRecord field it feeds, with the bound parameterized the
  same way runHook's defaultTimeoutMs already is.
- compact-basic: charsPerToken for the token estimator (default 4, the
  English-text heuristic; CJK-heavy deployments need ~1-2 or compaction
  fires far too late). Also corrects the BasicCompactService class doc,
  which claimed defaults the required-field config never had.
- fs-local: deletes the dead STREAM_MIN_SIZE constant and the dead
  FsIoInternals.streamMinSize seam — the read-routing bound lives in
  the consumer (tool-fs), where it is now config. This is item 1 of
  the proposed prune-write-only-fs-surface RFC, annotated accordingly.

Every new field gets range validation (following the existing
assertPositiveFinite pattern), a README row, and tests covering the
configured behavior, the schema default, and load-time rejection.

packages/bash/tool-bash/tests/tools.spec.ts

@@ -21,8 +21,8 @@ async function setup() {
   await ctx.plugin(SystemPrompt)
   await ctx.plugin(ToolRegistry)
   await ctx.plugin(AgentRegistry)
-  await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000 })
-  ;(ctx.bash as LocalBashExecutor).internals = { spillDir, graceMs: 200 }
+  await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000, graceMs: 200 })
+  ;(ctx.bash as LocalBashExecutor).internals = { spillDir }
   await ctx.plugin(ToolBash)
   return ctx
 }
@@ -184,8 +184,8 @@ describe('bash tool', () => {
     const ctx = new Context()
     await ctx.plugin(SystemPrompt)
     await ctx.plugin(ToolRegistry)
-    await ctx.plugin(LocalBashExecutor, { maxOutputBytes: 100 })
-    ;(ctx.bash as LocalBashExecutor).internals = { spillDir, graceMs: 200 }
+    await ctx.plugin(LocalBashExecutor, { maxOutputBytes: 100, graceMs: 200 })
+    ;(ctx.bash as LocalBashExecutor).internals = { spillDir }
     await ctx.plugin(ToolBash)
     const result = await call(ctx, 'bash', { command: 'for i in $(seq 1 100); do printf "line-%04d\\n" $i; done', description: 'test command' })
     expect(text(result)).toContain('[output truncated; full output: ')
@@ -316,8 +316,8 @@ describe('background tools', () => {
     const ctx = new Context()
     await ctx.plugin(SystemPrompt)
     await ctx.plugin(ToolRegistry)
-    await ctx.plugin(LocalBashExecutor, { maxOutputBytes: 100 })
-    ;(ctx.bash as LocalBashExecutor).internals = { spillDir, graceMs: 200 }
+    await ctx.plugin(LocalBashExecutor, { maxOutputBytes: 100, graceMs: 200 })
+    ;(ctx.bash as LocalBashExecutor).internals = { spillDir }
     await ctx.plugin(ToolBash)
 
     const started = await call(ctx, 'bash', { command: 'for i in $(seq 1 200); do printf "line-%04d\\n" $i; done', description: 'test command', run_in_background: true })
@@ -568,8 +568,8 @@ describe('background task ownership (cross-session isolation)', () => {
     const ctx = new Context()
     await ctx.plugin(SystemPrompt)
     await ctx.plugin(ToolRegistry)
-    await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000 })
-    ;(ctx.bash as LocalBashExecutor).internals = { spillDir, graceMs: 200 }
+    await ctx.plugin(LocalBashExecutor, { timeoutMs: 10_000, graceMs: 200 })
+    ;(ctx.bash as LocalBashExecutor).internals = { spillDir }
     const fiber = await ctx.plugin(ToolBash)
 
     const a = fakeAgent('sess-a')