docs(skill): hooks are a setting now, not who created the directory

The workspace-hooks install makes the skill's central hooks rule wrong in the
cautious direction. Six places told a worker that a linked case or a raw
workingDir has no `stop`/`blocked` and that send-and-wait cannot be trusted
there, so an agent would hand-roll output-marker synchronization in exactly the
workspaces where `wait:true` now works.

Rewritten against the setting rather than directory provenance:

- verbs.md §5.1: the where-to-spawn table, the rule paragraph (now naming
  `workspaceHooksEnabled`, default ON, the add-only merge, and the boot sweep of
  recovered sessions), and the silent-failure warning. The three cases that stay
  hook-less regardless are called out: remote SSH sessions, docker cases that
  opted out, and a workspace Codeman cannot write to.
- verbs.md §5.3: the send-and-wait precondition is "the workspace has the hooks
  block", not "a case Codeman created".
- endpoints.md: the Signals-by-mode table is now keyed on the setting, with rows
  for OFF, for remote/docker-opt-out, and for a session from an older server.
  The old create-path grep list becomes a "before 1.18.x" note.
- SKILL.md §2 + the cost list, recipes.md Flow-1 contrast, messaging.md step 1.

"Check, do not assume" is kept and promoted to the load-bearing habit, because
the setting is not visible from the call and a session created by an older server
that has not restarted still has nothing.

The `spawn_worker` hooks grep STAYS: it guards the setting being off, remote
sessions, and older servers. Only its diagnostic changes, since "pick an unused
name" is no longer the fix. That text lives in both the §0 heredoc and
`preamble.sh`, which `test/agent-skill.test.ts` pins byte-identical, so both are
patched with the same bytes.

Docs only, no behavior change. 23 skill tests green, full test:ci 5109 passed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

skills/codeman/preamble.sh

@@ -60,14 +60,14 @@ spawn_worker() {
   # NOT retryable in a loop: every quick-start failure code is terminal (§5.1).
   [ -n "$sid" ] || { jq -c '{error,errorCode}' <<<"$q" >&2; return 1; }
   [ "$mode" = claude ] || { printf '%s\n' "$sid"; return 0; }   # only claude draws a composer
-  # quick-start RESOLVES the name before creating: a linked case or an existing dir
-  # wins over a fresh scratch case, so "created => hooks" is only true after this one
-  # local grep (the same marker the server itself checks for). No marker means sendwait
-  # would false-resolve on flapping idle, possibly inside the user's REAL repo: refuse
-  # rather than run the job there.
+  # The server installs hooks into every claude workspace now, so this grep normally
+  # passes; it stays because the install is gated on a setting the operator can turn
+  # off, remote sessions never get hooks, and a session created by an older server
+  # still has none. No marker means sendwait would false-resolve on flapping idle,
+  # possibly inside the user's REAL repo: refuse rather than run the job there.
   cp=$(jq -r '.data.casePath // empty' <<<"$q")
   grep -qs '/api/hook-event' "$cp/.claude/settings.local.json" || {
-    echo "case '$name' resolved to '$cp', which has no Codeman hooks (linked or pre-existing?): pick an unused name, or work §5.1+§5.5 by hand" >&2
+    echo "case '$name' resolved to '$cp', which has no Codeman hooks (workspaceHooksEnabled off, remote, or an older server?): turn the setting on, or work §5.1+§5.5 by hand with markers" >&2
     delete_session "$sid" >/dev/null; return 1; }
   # Short composer wait FIRST, then the trust-dialog probe: a case still showing the
   # dialog can never pass the composer wait, so probing early keeps a cold case from