Fix column overflow and render math with KaTeX

- minmax(0,1fr)+min-width:0 and pre-wrap so a long fenced line no longer blows out the grid
- build-time KaTeX via @vscode/markdown-it-katex; ship katex CSS+fonts and link in layouts

yarn.lock

@@ -281,6 +281,13 @@
   dependencies:
     escape-string-regexp "^5.0.0"
 
+"@vscode/markdown-it-katex@^1.1.2":
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/@vscode/markdown-it-katex/-/markdown-it-katex-1.1.2.tgz#6ec355c5ec82d019f13a511e2363525384c91155"
+  integrity sha512-+4IIv5PgrmhKvW/3LpkpkGg257OViEhXkOOgCyj5KMsjsOfnRXkni8XAuuF9Ui5p3B8WnUovlDXAQNb8RJ/RaQ==
+  dependencies:
+    katex "^0.16.4"
+
 a-sync-waterfall@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/a-sync-waterfall/-/a-sync-waterfall-1.0.1.tgz#75b6b6aa72598b497a125e7a2770f14f4c8a1fa7"
@@ -430,6 +437,11 @@ commander@^5.1.0:
   resolved "https://registry.yarnpkg.com/commander/-/commander-5.1.0.tgz#46abbd1652f8e059bddaef99bbdcb2ad9cf179ae"
   integrity sha512-P0CysNDQ7rtVw4QIQtm+MRxV66vKFSvlsQvGYXZWR3qFU0jlMKHZZZgw8e+8DSah4UDKMqnknRDQz+xuQXQ/Zg==
 
+commander@^8.3.0:
+  version "8.3.0"
+  resolved "https://registry.yarnpkg.com/commander/-/commander-8.3.0.tgz#4837ea1b2da67b9c616a67afbb0fafee567bca66"
+  integrity sha512-OkTL9umf+He2DZkUq8f8J9of7yL6RJKI24dVITBmNfZBmri9zYZQrKkuXiKhyfPSu8tUhnVBB1iKXevvnlR4Ww==
+
 concat-map@0.0.1:
   version "0.0.1"
   resolved "https://registry.yarnpkg.com/concat-map/-/concat-map-0.0.1.tgz#d8a96bd77fd68df7793a73036a3ba0d5405d477b"
@@ -806,6 +818,20 @@ junk@^3.1.0:
   resolved "https://registry.yarnpkg.com/junk/-/junk-3.1.0.tgz#31499098d902b7e98c5d9b9c80f43457a88abfa1"
   integrity sha512-pBxcB3LFc8QVgdggvZWyeys+hnrNWg4OcZIU/1X59k5jQdLBlCsYGRQaz234SqoRLTCgMH00fY0xRJH+F9METQ==
 
+katex@^0.16.4:
+  version "0.16.47"
+  resolved "https://registry.yarnpkg.com/katex/-/katex-0.16.47.tgz#0a13a42c2deb4f74e61f162d440b9165a548030f"
+  integrity sha512-Eeo8Ys1doU1z+x8AZsPpQu+p/QcZBI5PeOo7QGQdy2x2m0MU/hYagBbGOmXwr5KVbEfVuWv9LpnQWeehogurjg==
+  dependencies:
+    commander "^8.3.0"
+
+katex@^0.17.0:
+  version "0.17.0"
+  resolved "https://registry.yarnpkg.com/katex/-/katex-0.17.0.tgz#536e25874ec9ac8728e3b4b7bf7fec6557b7dbf4"
+  integrity sha512-Vdw0ATsQ9V+LuegM/BTwQqV/6cTl5lbGcIrU+BCgLxyf6bo38ybOr372tuSIxir3CN720flu1meYR6XzNMwQnw==
+  dependencies:
+    commander "^8.3.0"
+
 keyv@^4.5.3:
   version "4.5.4"
   resolved "https://registry.yarnpkg.com/keyv/-/keyv-4.5.4.tgz#a879a99e29452f942439f2a405e3af8b31d4de93"