feat: workspaceHooksEnabled setting as the opt-out for workspace hook installs

Installing hooks into any workspace a Claude session runs in is the right
default, but it takes a decision away from a user who deliberately removed
them: nothing on disk distinguishes "removed on purpose" from "never had any",
so they would come back on the next session create.

Adds the synced workspaceHooksEnabled setting (App Settings -> Agents & CLIs ->
Claude), default ON. OFF restores the older behavior exactly: a Codeman hooks
block that is already present is still refreshed when stale (COD-91), but one
is never added.

Every create path routes through one applyWorkspaceHooks() helper so the gate
cannot apply to some paths only, and the boot-time recovery sweep honours it too.

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

src/web/public/index.html

@@ -1984,6 +1984,13 @@
                     </div>
                     <label class="switch switch-sm"><input type="checkbox" id="appSettingsAgentSkill"><span class="slider"></span></label>
                   </div>
+                  <div class="set-row" data-search="workspace hooks alerts approvals notifications settings.local.json">
+                    <div class="set-row-text">
+                      <span class="set-row-label">Workspace Hooks</span>
+                      <span class="set-row-desc">Install Codeman's hooks in each Claude workspace, so tab alerts, the Approvals Inbox and idle detection also work in linked cases and existing repos. Off leaves your repos untouched.</span>
+                    </div>
+                    <label class="switch switch-sm"><input type="checkbox" id="appSettingsWorkspaceHooks"><span class="slider"></span></label>
+                  </div>
                   <div class="set-row" data-search="remote auto reconnect ssh">
                     <div class="set-row-text">
                       <span class="set-row-label">Remote auto-reconnect</span>