Rework and fix stopwatch (#30732)

Fixes https://github.com/go-gitea/gitea/issues/30721 and overhauls the
stopwatch. Time is now shown inside the "dot" icon and on both mobile
and desktop. All rendering is now done by `<relative-time>`, the
`pretty-ms` dependency is dropped.

Desktop:
<img width="557" alt="Screenshot 2024-04-29 at 22 33 27"
src="https://github.com/go-gitea/gitea/assets/115237/3a46cdbf-6af2-4bf9-b07f-021348badaac">

Mobile:
<img width="640" alt="Screenshot 2024-04-29 at 22 34 19"
src="https://github.com/go-gitea/gitea/assets/115237/8a2beea7-bd5d-473f-8fff-66f63fd50877">

Note for tippy:
Previously, tippy instances defaulted to "menu" theme, but that theme is
really only meant for `.ui.menu`, so it was not optimal for the
stopwatch popover.

This introduces a unopinionated `default` theme that has no padding and
should be suitable for all content. I reviewed all existing uses and
explicitely set the desired `theme` on all of them.

package-lock.json

@@ -42,7 +42,6 @@
         "postcss": "8.4.38",
         "postcss-loader": "8.1.1",
         "postcss-nesting": "12.1.2",
-        "pretty-ms": "9.0.0",
         "sortablejs": "1.15.2",
         "swagger-ui-dist": "5.17.2",
         "tailwindcss": "3.4.3",
@@ -9170,17 +9169,6 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
-    "node_modules/parse-ms": {
-      "version": "4.0.0",
-      "resolved": "https://registry.npmjs.org/parse-ms/-/parse-ms-4.0.0.tgz",
-      "integrity": "sha512-TXfryirbmq34y8QBwgqCVLi+8oA3oWx2eAnSn62ITyEhEYaWRlVZ2DvMM9eZbMs/RfxPu/PK/aBLyGj4IrqMHw==",
-      "engines": {
-        "node": ">=18"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/sindresorhus"
-      }
-    },
     "node_modules/path-exists": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/path-exists/-/path-exists-4.0.0.tgz",
@@ -9772,20 +9760,6 @@
         "url": "https://github.com/chalk/ansi-styles?sponsor=1"
       }
     },
-    "node_modules/pretty-ms": {
-      "version": "9.0.0",
-      "resolved": "https://registry.npmjs.org/pretty-ms/-/pretty-ms-9.0.0.tgz",
-      "integrity": "sha512-E9e9HJ9R9NasGOgPaPE8VMeiPKAyWR5jcFpNnwIejslIhWqdqOrb2wShBsncMPUb+BcCd2OPYfh7p2W6oemTng==",
-      "dependencies": {
-        "parse-ms": "^4.0.0"
-      },
-      "engines": {
-        "node": ">=18"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/sindresorhus"
-      }
-    },
     "node_modules/printable-characters": {
       "version": "1.0.42",
       "resolved": "https://registry.npmjs.org/printable-characters/-/printable-characters-1.0.42.tgz",