feat(themes): add gruvbox, rosé pine, tokyo night, and solarized dark

Tier 2 community themes mapped to nib's token system.
Total theme count: 10 (3 original + 3 tier 1 + 4 tier 2).

web/style.css

@@ -140,6 +140,94 @@
     --lineage: #ff79c6;
 }
 
+[data-theme="gruvbox"] {
+    color-scheme: dark;
+    --bg: #282828;
+    --surf: #1d2021;
+    --raised: #3c3836;
+    --border: #504945;
+    --soft: #32302f;
+    --text: #ebdbb2;
+    --muted: #a89984;
+    --dim: #665c54;
+    --accent: #fabd2f;
+    --a-bg: rgba(250,189,47,.09);
+    --a-str: rgba(250,189,47,.22);
+    --todo: #fabd2f;
+    --note: #8ec07c;
+    --event: #83a598;
+    --remind: #fe8019;
+    --ok: #b8bb26;
+    --danger: #fb4934;
+    --lineage: #d3869b;
+}
+
+[data-theme="rosepine"] {
+    color-scheme: dark;
+    --bg: #191724;
+    --surf: #1f1d2e;
+    --raised: #26233a;
+    --border: #403d52;
+    --soft: #211f30;
+    --text: #e0def4;
+    --muted: #908caa;
+    --dim: #6e6a86;
+    --accent: #c4a7e7;
+    --a-bg: rgba(196,167,231,.09);
+    --a-str: rgba(196,167,231,.22);
+    --todo: #f6c177;
+    --note: #9ccfd8;
+    --event: #31748f;
+    --remind: #ea9a97;
+    --ok: #a6da95;
+    --danger: #eb6f92;
+    --lineage: #c4a7e7;
+}
+
+[data-theme="tokyonight"] {
+    color-scheme: dark;
+    --bg: #1a1b26;
+    --surf: #16161e;
+    --raised: #292e42;
+    --border: #3b4261;
+    --soft: #1f2335;
+    --text: #c0caf5;
+    --muted: #a9b1d6;
+    --dim: #565f89;
+    --accent: #7aa2f7;
+    --a-bg: rgba(122,162,247,.09);
+    --a-str: rgba(122,162,247,.22);
+    --todo: #e0af68;
+    --note: #7dcfff;
+    --event: #7aa2f7;
+    --remind: #ff9e64;
+    --ok: #9ece6a;
+    --danger: #f7768e;
+    --lineage: #bb9af7;
+}
+
+[data-theme="solarized"] {
+    color-scheme: dark;
+    --bg: #002b36;
+    --surf: #073642;
+    --raised: #094552;
+    --border: #586e75;
+    --soft: #05303b;
+    --text: #839496;
+    --muted: #657b83;
+    --dim: #586e75;
+    --accent: #268bd2;
+    --a-bg: rgba(38,139,210,.09);
+    --a-str: rgba(38,139,210,.22);
+    --todo: #b58900;
+    --note: #2aa198;
+    --event: #268bd2;
+    --remind: #cb4b16;
+    --ok: #859900;
+    --danger: #dc322f;
+    --lineage: #6c71c4;
+}
+
 /* ── RESET ──────────────────────────────────────────── */
 *, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
 html, body { height: 100%; overflow: hidden; }