feat: add Kropáček Ondřej + May–Jul feature work (half-cell marks, copy/paste, exports, roles)

New worker: Kropáček Ondřej (TKB, part-time student) inserted between
Dvořák Václav and Vondrák Pavel in data.json, the full-month Excel
template (new row 13, everything below shifted) and the docházka
template (13 person rows). Not added to the harmonogram/CIS roster —
he has no CIS personal number.

Also checkpoints the uncommitted work deployed to production between
May and July 2026:
- half-cell day/night preference marks (color + text per half)
- cell copy/paste (Ctrl+C/V, context menu), incl. from info rows
- light/dark theme toggle, TKB people filter, 162 filter
- full-month Excel export (template) and harmonogram export for CIS
- docházka export: half-time workers, retired flag, contractor handling
- third login role "cis" (viewer + export access)
- retired flag hides a person from UI/FPD while keeping past data

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

web/src/index.css

@@ -3,8 +3,8 @@
 body {
   margin: 0;
   font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
-  background: #0f172a;
-  color: #e2e8f0;
+  background: var(--color-slate-900);
+  color: var(--color-slate-200);
 }
 
 #root {
@@ -15,13 +15,44 @@ body {
   width: 8px;
   height: 8px;
 }
-::-webkit-scrollbar-track {
-  background: #1e293b;
+::-webkit-scrollbar-track { background: var(--color-slate-800); }
+::-webkit-scrollbar-thumb { background: var(--color-slate-600); border-radius: 4px; }
+::-webkit-scrollbar-thumb:hover { background: var(--color-slate-500); }
+
+/* PMS column (Práce mimo směnu) — month-boundary marker.
+   Dark mode: matches the original bg-slate-700/30 tint. */
+.pms-cell,
+.pms-week {
+  background-color: color-mix(in oklab, var(--color-slate-700) 30%, transparent);
 }
-::-webkit-scrollbar-thumb {
-  background: #475569;
-  border-radius: 4px;
-}
-::-webkit-scrollbar-thumb:hover {
-  background: #64748b;
+.pms-label { background-color: #283040; }
+.pms-label-text { color: var(--color-slate-300); }
+
+/* ============================================================
+   LIGHT THEME
+   Implemented by inverting the slate color scale via CSS variables.
+   Browser only re-evaluates the variable, no rule matching, no !important.
+   ============================================================ */
+body.light {
+  --color-slate-900: #f8fafc;
+  --color-slate-800: #ffffff;
+  --color-slate-700: #e2e8f0;
+  --color-slate-600: #cbd5e1;
+  --color-slate-500: #94a3b8;
+  --color-slate-400: #64748b;
+  --color-slate-300: #334155;
+  --color-slate-200: #1e293b;
+  --color-slate-100: #0f172a;
+  --color-slate-50:  #020617;
 }
+
+/* Light-mode specific tweaks where simple inversion isn't enough.
+   These selectors win on specificity (.light + .class > Tailwind's single class). */
+body.light .bg-slate-800\/50 { background-color: #dbeafe; }   /* weekend cells in person rows */
+body.light .bg-slate-700\/30 { background-color: #dbeafe; }   /* weekend cells in info rows */
+body.light .schedule-wrapper { background-color: #ffffff; }
+body.light .pms-cell,
+body.light .pms-week { background-color: #fde68a; }
+body.light .pms-week { box-shadow: inset 1px 0 0 #94a3b8, inset -1px 0 0 #94a3b8; }
+body.light .pms-label { background-color: #fde68a; }
+body.light .pms-label-text { color: #78350f; }