Add create-workstream: MCP tool, CLI commands, dashboard hint

MCP server: add create_workstream(topic_id, title, slug?, owner?,
  description?, due_date?) — auto-generates slug from title if omitted;
  emits workstream_created progress event. Now 12 tools total.

CLI: add two new subcommands —
  custodian create-workstream --domain DOMAIN --title TITLE [--slug] [--owner] [--description]
  custodian create-task --workstream ID_OR_SLUG --title TITLE [--priority] [--assignee]
  create-task accepts workstream UUID or slug (resolves via API).

Dashboard: hint box below "Open Workstreams by Domain" chart listing
  registered domains that have zero workstreams, with the exact
  custodian create-workstream command to run.

TOOLS.md: updated tool count (11 → 12) and added create_workstream row.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dashboard/src/index.md

@@ -134,6 +134,26 @@ display(Plot.plot({
 }));
 ```
 
+```js
+// Registered domains with no workstreams yet — show a getting-started hint
+const regs = regsState ?? [];
+const registeredDomains = new Set(regs.map(e => e.detail?.domain).filter(Boolean));
+const emptyRegistered = (summary.topics ?? []).filter(t =>
+  registeredDomains.has(t.domain) && (t.workstreams ?? []).length === 0
+);
+
+if (emptyRegistered.length > 0) {
+  display(html`<div class="hint-box">
+    <strong>💡 Getting started</strong>
+    <p>These registered projects have no workstreams yet:</p>
+    <ul>${emptyRegistered.map(t => html`<li>
+      <strong>${t.domain}</strong> — open the repo in Claude Code and ask the Custodian to create one, or run:<br>
+      <code>custodian create-workstream --domain ${t.domain} --title "My first workstream"</code>
+    </li>`)}</ul>
+  </div>`);
+}
+```
+
 ## Blocking Decisions
 
 ```js
@@ -183,4 +203,6 @@ display(Inputs.table((summary.recent_progress ?? []).map(e => ({
 .card.warn { border: 2px solid orange; }
 .big-num { font-size: 2.5rem; font-weight: bold; margin: 0.25rem 0; }
 .warning { background: #fff3cd; border: 1px solid #ffc107; border-radius: 4px; padding: 0.75rem; }
+.hint-box { background: var(--theme-background-alt); border-left: 3px solid steelblue; border-radius: 4px; padding: 0.75rem 1rem; margin-top: 0.75rem; font-size: 0.9rem; }
+.hint-box code { background: var(--theme-background); padding: 0.15rem 0.4rem; border-radius: 3px; font-size: 0.85rem; }
 </style>