Add shift planning, month closure + payroll, and a dark modern redesign

Ports two modules from the friend's Google Apps Script build (kept as
reference in gscript/) onto the TypeScript stack, rewritten cleanly against
this app's own data model rather than copied 1:1:

- Shift planning: weekly template (Sun-Thu evening, Fri/Sat two slots),
  lazy idempotent generation per period (no cron needed), employee
  signup/cancel with collision + capacity checks, admin calendar view with
  slot editing and manual assignment.
- Month closure + payroll: employee confirms the month (blocked while a
  shift is still open), admin locks and finalizes pay (base hours * rate +
  tips/bonus/other), reopen to undo a premature lock, mark paid. Pay rates
  are versioned by date, defaulting the first-ever rate to apply
  retroactively to the employee's whole history.
- A shift left open more than 12h (forgotten clock-out) is auto-closed at
  clock_in + 12h, checked lazily on read instead of a background job.
- Full dark, sharp-edged modern restyle (theme.css replaces tui.css) with
  an amber accent, keeping every existing class name so no component
  logic needed to change.

Backend test coverage (jest) for all three workflows: shift planning,
closure/payroll, and the forgotten-clock-out auto-close.

gscript/NewsService.js

@@ -0,0 +1,55 @@
+function getNewsForUser_(user, emp) {
+  const now = now_();
+  const memberships = rows_(CFG.SHEETS.USER_COMPANIES)
+    .filter(x => String(x.user_id) === String(user.user_id))
+    .map(x => String(x.company_id));
+
+  return rows_(CFG.SHEETS.NEWS)
+    .filter(n => n.active === true || String(n.active).toUpperCase() === 'TRUE')
+    .filter(n => !n.published_from || new Date(n.published_from) <= now)
+    .filter(n => !n.published_to || new Date(n.published_to) >= now)
+    .filter(n => !n.target_role || String(n.target_role) === 'ALL' || String(n.target_role) === String(user.role))
+    .filter(n => !n.company_id || memberships.includes(String(n.company_id)) || (emp && String(emp.company_id) === String(n.company_id)))
+    .filter(n => !n.location_id || (emp && String(emp.location_id) === String(n.location_id)))
+    .sort((a,b)=>new Date(b.created_at)-new Date(a.created_at))
+    .map(n => ({
+      news_id:n.news_id,title:n.title,content:n.content,category:n.category,
+      require_confirmation:n.require_confirmation,created_at:n.created_at
+    }));
+}
+
+function publishNews(token, data) {
+  const user = requireUser_(token,['ADMIN','MANAGER']);
+  const n = {
+    news_id:uuid_('NEWS'),
+    title:String(data.title || '').trim(),
+    content:String(data.content || '').trim(),
+    category:String(data.category || 'INFO'),
+    company_id:String(data.company_id || ''),
+    location_id:String(data.location_id || ''),
+    target_role:String(data.target_role || 'ALL'),
+    published_from:data.published_from || now_(),
+    published_to:data.published_to || '',
+    require_confirmation:!!data.require_confirmation,
+    active:true,
+    created_by:user.user_id,
+    created_at:now_()
+  };
+  if (!n.title) throw new Error('Titulek je povinný.');
+  append_(CFG.SHEETS.NEWS,n);
+  audit_(user.user_id,'NEWS_PUBLISHED','NEWS',n.news_id,'',n);
+  return {ok:true,news_id:n.news_id};
+}
+
+function confirmNews(token, newsId) {
+  const user = requireUser_(token);
+  let r = findOne_(CFG.SHEETS.NEWS_READS, x => String(x.news_id)===String(newsId) && String(x.user_id)===String(user.user_id));
+  if (r) {
+    updateBy_(CFG.SHEETS.NEWS_READS,'news_read_id',r.news_read_id,{read_at:r.read_at || now_(),confirmed_at:now_()});
+  } else {
+    append_(CFG.SHEETS.NEWS_READS,{
+      news_read_id:uuid_('NREAD'),news_id:newsId,user_id:user.user_id,read_at:now_(),confirmed_at:now_()
+    });
+  }
+  return {ok:true};
+}