Easy accessibility fixes

[arildm]

The Wave browser extension reports some issues that are easy to fix:

• Some images are missing alt text
• Some buttons and tables are missing text
• The language selector is missing a label
• There is no h1 heading

Another issue is the contrast on some links (orange on white or light gray) and buttons (white on blue). We can look into it but it doesn't seem as easy to fix.

[arildm]

Fixed in these recent commits:

• 14f377f - fix(a11y): h1 on Home (Tue Nov 19 13:45:08 2024 +0100)
• ...
• f38c3c9 - style(a11y): links underlined, not orange (Tue Nov 19 10:18:33 2024 +0100)
• 25061b4 - style(a11y): brighter progress bar (Tue Nov 19 10:17:28 2024 +0100)
• ec8dbda - fix(a11y): warning button dark (Tue Nov 19 10:07:46 2024 +0100)
• 97d8dd1 - fix(a11y): dark mode contrast (Mon Nov 18 18:44:51 2024 +0100)
• a7b4d21 - fix(a11y): darker orange (Mon Nov 18 18:23:06 2024 +0100)
• a23b6a9 - fix(a11y): more contrast (Mon Nov 18 18:18:24 2024 +0100)
• 628ad9a - fix(a11y): avoid redundant adjacent links (Mon Nov 18 18:18:24 2024 +0100)
• 28425a3 - fix(a11y): empty th, button (Mon Nov 18 18:18:20 2024 +0100)
• 9de8c35 - fix(a11y): better tab key navigation (Mon Nov 18 17:24:05 2024 +0100)
• 0d2c6d5 - fix(a11y): orphaned label for identifier (Mon Nov 18 17:05:31 2024 +0100)
• e56638d - fix(a11y): LocaleSwitcher hidden label (Mon Nov 18 16:58:43 2024 +0100)
• d7973ca - fix(a11y): img alt (Mon Nov 18 16:48:09 2024 +0100)