Improve context popup rendering (#30824) (#30829)

Backport #30824 by @silverwind

Before, lot of empty space when no labels or body:

<img width="281" alt="Screenshot 2024-05-02 at 13 51 29"
src="https://github.com/go-gitea/gitea/assets/115237/8a980ccd-d53c-43a3-a059-dc8c614621e1">

After, empty space collapsed:

<img width="306" alt="Screenshot 2024-05-02 at 13 51 16"
src="https://github.com/go-gitea/gitea/assets/115237/8d9c154d-5de1-43d0-8536-afd9194d99b3">

All `<p>` (unsuitable) and `<small>` (discouraged in favor of css) tags
are removed.

Co-authored-by: silverwind <me@silverwind.io>

web_src/js/components/.eslintrc.yaml

@@ -18,4 +18,5 @@ rules:
   vue/attributes-order: [0]
   vue/html-closing-bracket-spacing: [2, {startTag: never, endTag: never, selfClosingTag: never}]
   vue/max-attributes-per-line: [0]
+  vue/singleline-html-element-content-newline: [0]
   vue-scoped-css/enforce-style-type: [0]

web_src/js/components/ContextPopup.vue

@@ -91,16 +91,22 @@ export default {
 <template>
   <div ref="root">
     <div v-if="loading" class="tw-h-12 tw-w-12 is-loading"/>
-    <div v-if="!loading && issue !== null">
-      <p><small>{{ issue.repository.full_name }} on {{ createdAt }}</small></p>
-      <p><svg-icon :name="icon" :class="['text', color]"/> <strong>{{ issue.title }}</strong> #{{ issue.number }}</p>
-      <p>{{ body }}</p>
+    <div v-if="!loading && issue !== null" class="tw-flex tw-flex-col tw-gap-2">
+      <div class="tw-text-12">{{ issue.repository.full_name }} on {{ createdAt }}</div>
+      <div class="flex-text-block">
+        <svg-icon :name="icon" :class="['text', color]"/>
+        <span class="issue-title tw-font-semibold tw-break-anywhere">
+          {{ issue.title }}
+          <span class="index">#{{ issue.number }}</span>
+        </span>
+      </div>
+      <div v-if="body">{{ body }}</div>
       <!-- eslint-disable-next-line vue/no-v-html -->
-      <div v-html="renderedLabels"/>
+      <div v-if="issue.labels.length" v-html="renderedLabels"/>
     </div>
-    <div v-if="!loading && issue === null">
-      <p><small>{{ i18nErrorOccurred }}</small></p>
-      <p>{{ i18nErrorMessage }}</p>
+    <div class="tw-flex tw-flex-col tw-gap-2" v-if="!loading && issue === null">
+      <div class="tw-text-12">{{ i18nErrorOccurred }}</div>
+      <div>{{ i18nErrorMessage }}</div>
     </div>
   </div>
 </template>