i18n: extract shared strings into the existing common namespace

Part of #145.

Fourteen files whose user-facing strings are generic enough to belong in
`common` — loading and empty states, the confirmation modal, the shared
input modals (text/date/user/attachment viewer), the mobile nav bar, the
autocomplete input, the error screen and the file-upload error paths.

Extends the namespace that already exists, so `src/i18n/config.js` is
untouched and this cannot collide with any other extraction PR over the
`ns:` array. 28 keys added to `public/locales/en/common.json`.

English only — no translations, no behaviour change. Every t() value is
checked against this branch's base: the string must appear
character-for-character in the code it replaces (36 call sites).

One value is matched loosely and worth naming: `errorScreen.hideDetails`.
The base renders `{showDetails ? 'Hide' : 'Show'} error details`, so
neither full phrase exists contiguously in the source — only one branch of
the ternary can. Both keys hold exactly what each branch renders. The
sentence is kept whole rather than split around the ternary, because a
split sentence cannot be reordered by a translator.

src/hooks/useFileUpload.js

@@ -5,12 +5,14 @@ import { useUserProfile } from '../queries/UserQueries'
 import { useNotification } from '../service/NotificationProvider'
 import { apiClient } from '../utils/ApiClient'
 import { isPlusAccount, resolvePhotoURL } from '../utils/Helpers'
+import { useTranslation } from 'react-i18next'
 
 export const useFileUpload = ({
   draftId,
   entityId,
   entityType = 'chore_attachment',
 } = {}) => {
+  const { t } = useTranslation('common')
   const { showError } = useNotification()
   const { data: userProfile } = useUserProfile()
 
@@ -58,14 +60,14 @@ export const useFileUpload = ({
 
         if (response.status === 507) {
           showError({
-            title: 'Storage Quota Exceeded',
-            message: 'You have exceeded your quota for uploading files.',
+            title: t('upload.quotaTitle'),
+            message: t('upload.quotaMessage'),
           })
           return null
         } else if (response.status === 413) {
           showError({
-            title: 'File Too Large',
-            message: 'The file you are trying to upload is too large.',
+            title: t('upload.tooLargeTitle'),
+            message: t('upload.tooLargeMessage'),
           })
           return null
         } else if (response.status === 403 && !isPlusAccount(userProfile)) {
@@ -76,8 +78,8 @@ export const useFileUpload = ({
           return null
         } else if (response.status === 403) {
           showError({
-            title: 'Permission Denied',
-            message: 'You do not have permission to upload files.',
+            title: t('upload.deniedTitle'),
+            message: t('upload.deniedMessage'),
           })
           return null
         } else if (!response.ok) {
@@ -105,7 +107,7 @@ export const useFileUpload = ({
         return null
       }
     },
-    [entityType, entityId, draftId, showError, userProfile],
+    [entityType, entityId, draftId, showError, userProfile, t],
   )
 
   return { uploadFile, isPlus: isPlusAccount(userProfile) }