flow.html: add SCH3DUL3S to cross-page tab strip (closes #489)

mara: "why can this even be an issue?" — fair. The SCH3DUL3S
tab was added to index.html's chrome in #459 but flow.html's
parallel tab strip was never updated to match. The flow page
operator hit a dead end going back to the schedules pane.

One-line fix: copy the same `<a class="tab" href="/#schedules"
role="tab" data-tab="schedules">` link from index.html into
flow.html's chrome, positioned between SYST3M and FL0W to match
the dashboard ordering. Count pill stays hidden (flow.js
doesn't sync `schedulesState` — same reason SW4RM/Y3R C4LL/
SYST3M pills also stay hidden on this page).

frontend/packages/dashboard/src/flow.html

@@ -29,6 +29,10 @@
         <span class="tab-label">◆ SYST3M ◆</span>
         <span class="tab-count" id="tab-count-system" hidden></span>
       </a>
+      <a class="tab" href="/#schedules" role="tab" data-tab="schedules">
+        <span class="tab-label">◆ SCH3DUL3S ◆</span>
+        <span class="tab-count" id="tab-count-schedules" hidden></span>
+      </a>
       <a class="tab tab-link active" id="tab-flow" href="/flow.html"
          aria-current="page"
          title="all-agents chat — you are here">