Remove dead CSS (#37376)

Removes CSS rules that have zero usages across templates, Go source,
JS/TS/Vue, and `options/`. Each selector was cross-checked for runtime
additions (Fomantic JS, library classes) before removal.

A few rules with no current usages are kept as symmetric pairs of
heavily-used classes likely to be needed:
- `.ui.bottom.attached.header` / `.ui.bottom.attached.message` — pair
with the widely-used `top.attached` variants
- `.ui.warning.header` / `.ui.warning.segment` — warning-themed variants
of error-themed classes that are kept
- `.btn.small` — size variant alongside the kept `.btn.tiny`

---
This PR was written with the help of Claude Opus 4.7

---------

Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>

web_src/css/modules/table.css

@@ -226,18 +226,10 @@
 .ui.table td.six.wide {
   width: 37.5%;
 }
-.ui.table th.seven.wide,
-.ui.table td.seven.wide {
-  width: 43.75%;
-}
 .ui.table th.eight.wide,
 .ui.table td.eight.wide {
   width: 50%;
 }
-.ui.table th.nine.wide,
-.ui.table td.nine.wide {
-  width: 56.25%;
-}
 .ui.table th.ten.wide,
 .ui.table td.ten.wide {
   width: 62.5%;
@@ -246,26 +238,6 @@
 .ui.table td.eleven.wide {
   width: 68.75%;
 }
-.ui.table th.twelve.wide,
-.ui.table td.twelve.wide {
-  width: 75%;
-}
-.ui.table th.thirteen.wide,
-.ui.table td.thirteen.wide {
-  width: 81.25%;
-}
-.ui.table th.fourteen.wide,
-.ui.table td.fourteen.wide {
-  width: 87.5%;
-}
-.ui.table th.fifteen.wide,
-.ui.table td.fifteen.wide {
-  width: 93.75%;
-}
-.ui.table th.sixteen.wide,
-.ui.table td.sixteen.wide {
-  width: 100%;
-}
 
 .ui.basic.table {
   background: transparent;