fix(ui): soften dark-mode text colors to reduce glare

The three dark-mode text tiers all sat close to white (15.5 / 11.1 / 8.4
contrast on the app background), so screens full of table data and labels
looked harsh and the hierarchy flattened.

- --text-1 #f4f4f5 -> #e4e4e7, and the shadcn --foreground family follows
  so inherited body text matches
- --text-2 #d0d0d8 -> #ababb3, --text-3 #b5b5bd -> #9a9aa2
- --muted-foreground aligned with --text-2

Contrast is now about 13.4 / 7.5 / 6.1; the secondary and tertiary tiers
stay at or above 4.5:1 on card and selected backgrounds. Light mode is
unchanged.

docs/design-system.html

@@ -67,7 +67,7 @@
       --action-bg: #ea580c; --action-hover: #f06d1f; --action-fg: #ffffff; --action-text: #fb923c; --action-soft: rgba(249, 115, 21, 0.12); --ring: #d77a3c;
       --bg-app: #1c1c1e; --bg-sidebar: #161618; --bg-subtle: #26262a; --bg-selected: #313136; --bg-card: #2e2e33;
       --border: #3e3e45; --border-strong: #4a4a52;
-      --text-1: #f4f4f5; --text-2: #d0d0d8; --text-3: #b5b5bd;
+      --text-1: #e4e4e7; --text-2: #ababb3; --text-3: #9a9aa2;
       --inverse-bg: #f4f4f5; --inverse-fg: #18181b; --overlay: rgba(0, 0, 0, .55); --control-off: #6f6f77;
       --direct-fill: #4a8fd9; --direct-text: #8fb8e6; --direct-soft: rgba(74, 143, 217, 0.12); --direct-solid: #2f6db3; --direct-on: #ffffff;
       --route-fill: #2a9d8f; --route-text: #7cc4ba; --route-soft: rgba(42, 157, 143, 0.12); --route-solid: #1f7d72; --route-on: #ffffff;
@@ -86,7 +86,7 @@
     --action-bg: #ea580c; --action-hover: #f06d1f; --action-fg: #ffffff; --action-text: #fb923c; --action-soft: rgba(249, 115, 21, 0.12); --ring: #d77a3c;
     --bg-app: #1c1c1e; --bg-sidebar: #161618; --bg-subtle: #26262a; --bg-selected: #313136; --bg-card: #2e2e33;
     --border: #3e3e45; --border-strong: #4a4a52;
-    --text-1: #f4f4f5; --text-2: #d0d0d8; --text-3: #b5b5bd;
+    --text-1: #e4e4e7; --text-2: #ababb3; --text-3: #9a9aa2;
     --inverse-bg: #f4f4f5; --inverse-fg: #18181b; --overlay: rgba(0, 0, 0, .55); --control-off: #6f6f77;
     --direct-fill: #4a8fd9; --direct-text: #8fb8e6; --direct-soft: rgba(74, 143, 217, 0.12); --direct-solid: #2f6db3; --direct-on: #ffffff;
     --route-fill: #2a9d8f; --route-text: #7cc4ba; --route-soft: rgba(42, 157, 143, 0.12); --route-solid: #1f7d72; --route-on: #ffffff;

src/index.css

@@ -37,22 +37,23 @@
 
   .dark {
     --background: 240 3.4% 11.4%;
-    --foreground: 240 4.8% 95.9%;
+    /* 文字色与下方 --text-1 一致（#e4e4e7）：纯白主文字铺满整屏时刺眼 */
+    --foreground: 240 5.9% 90%;
     --card: 240 5.2% 19%;
-    --card-foreground: 240 4.8% 95.9%;
+    --card-foreground: 240 5.9% 90%;
     --popover: 240 5.2% 19%;
-    --popover-foreground: 240 4.8% 95.9%;
+    --popover-foreground: 240 5.9% 90%;
 
     --primary: 240 4.8% 95.9%;
     --primary-foreground: 240 5.9% 10%;
 
     --secondary: 240 5% 15.7%;
-    --secondary-foreground: 240 4.8% 95.9%;
+    --secondary-foreground: 240 5.9% 90%;
 
     --muted: 240 5% 15.7%;
-    --muted-foreground: 240 5.7% 72.5%;
+    --muted-foreground: 240 5.4% 68.6%;
     --accent: 240 5% 15.7%;
-    --accent-foreground: 240 4.8% 95.9%;
+    --accent-foreground: 240 5.9% 90%;
 
     --destructive: 0 62.8% 30.6%;
     --destructive-foreground: 0 0% 98%;
@@ -154,9 +155,11 @@
     --bg-selected: #313136;
     --bg-card: #2e2e33;
     --border-strong: #4a4a52;
-    --text-1: #f4f4f5;
-    --text-2: #d0d0d8;
-    --text-3: #b5b5bd;
+    /* 三档文字都比纯白压低一截并拉开明度差：太亮时三档都贴近白色，整屏显得刺眼、层次压平。
+       次级、三级对卡片底、选中底（--bg-card / --bg-selected）都 ≥ 4.5:1 */
+    --text-1: #e4e4e7;
+    --text-2: #ababb3;
+    --text-3: #9a9aa2;
     /* 深色模式：实心块压暗一档（大面积不刺眼）+ 白字；文字、焦点描边用亮一档的 #fb923c */
     --action-bg: #ea580c;
     --action-fg: #ffffff;