Apply velvet-table redesign, fix game lifecycle and history bugs

Frontend:
- Dark green/gold "velvet table" visual redesign across the whole app
  (Auth, Lobby, GameList, GameTable, History, GameOver, modals), with
  Playfair Display/DM Sans typography and a centralized Tailwind palette.
- Desktop game table fit-scales to fill the window; mobile gets
  overlapping hand/trick layouts and larger touch-friendly cards.
- Standings sidebar now groups completed rounds by series with a
  per-series subtotal row, struck-through tips on missed bids.
- History page rewritten into a scoreboard-style detail view (player
  totals beside names, series grouped 2-up on desktop / stacked on
  mobile) and gained game names, completed/abandoned status, and a
  button to reopen a prematurely-ended game back into the lobby.

Backend:
- Fix started games being deleted from memory (and vanishing from
  everyone's lobby) when all players disconnect; only `end_game` tears
  down a started game now.
- Fix a crash writing a timezone-aware datetime into the naive
  `ended_at` Postgres column.
- Add `reopen_game`/`restore_game` to un-end a prematurely-ended game
  from history and resume it from the lobby.
- Let any seated player end an abandoned game once the host is
  offline, not just the host, so the game isn't stuck forever.
- Expose SERIES_PER_GAME/ROUNDS_PER_SERIES as named constants on the
  engine so the persistence layer derives game-completion rules from
  bridzik.py instead of re-encoding them.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/tailwind.config.js

@@ -1,6 +1,63 @@
 /** @type {import('tailwindcss').Config} */
 export default {
   content: ['./index.html', './src/**/*.{ts,tsx}'],
-  theme: { extend: {} },
+  theme: {
+    extend: {
+      colors: {
+        // Velvet table palette (design handoff: "01 — Sametový stôl")
+        table: '#090e0b',
+        header: '#070c09',
+        circle: '#0c1a0f',
+        'circle-active': '#0e2015',
+        gold: '#c9a84c',
+        'gold-bright': '#f0d060',
+        'gold-dim': '#e8c14a',
+        // Secondary text is warm cream (not green) for legibility on the dark
+        // table — the green is reserved for structure (felt, opponent cards).
+        'green-dim': '#9c906c',
+        'green-score': '#d8cba6',
+        'green-circle': '#c2b58c',
+      },
+      fontFamily: {
+        serif: ['"Playfair Display"', 'Georgia', 'serif'],
+        sans: ['"DM Sans"', 'system-ui', 'sans-serif'],
+      },
+      keyframes: {
+        // turn-pulse — blinking dot / placeholder slot
+        tp: { '0%,100%': { opacity: '1' }, '50%': { opacity: '.5' } },
+        // card-in — card lands on the table
+        ci: {
+          from: { opacity: '0', transform: 'translateY(-6px) scale(.9)' },
+          to: { opacity: '1', transform: 'none' },
+        },
+        // active-ring — glowing gold ring around the active player circle
+        ar: {
+          '0%,100%': {
+            boxShadow:
+              '0 0 0 3px rgba(201,168,76,.18),0 0 18px rgba(201,168,76,.5),0 0 42px rgba(201,168,76,.2)',
+          },
+          '50%': {
+            boxShadow:
+              '0 0 0 5px rgba(201,168,76,.34),0 0 32px rgba(201,168,76,.85),0 0 56px rgba(201,168,76,.3)',
+          },
+        },
+        // glow-1 — gold glow border on a playable card
+        g1: {
+          '0%,100%': {
+            boxShadow: '0 0 18px rgba(201,168,76,.55),0 6px 18px rgba(0,0,0,.55)',
+          },
+          '50%': {
+            boxShadow: '0 0 34px rgba(201,168,76,.85),0 6px 18px rgba(0,0,0,.55)',
+          },
+        },
+      },
+      animation: {
+        tp: 'tp 1.8s ease-in-out infinite',
+        ci: 'ci .3s ease both',
+        ar: 'ar 2.2s ease-in-out infinite',
+        g1: 'g1 2.2s ease-in-out infinite',
+      },
+    },
+  },
   plugins: [],
 };