Various fixes and improvements (#1643)

- allow repo names to be case-insensitive
- improve backend error handling on DB get errors (record not found ->
404, else -> 500)
- replace magic numbers of http response codes
- unify the look and feel of cancel / save buttons on forms and view
them in one line

---------

Co-authored-by: Lauris BH <lauris@nix.lv>

web/src/components/admin/settings/AdminAgentsTab.vue

@@ -78,7 +78,7 @@
             :label="$t('admin.settings.agents.capacity.capacity')"
             docs-url="docs/next/administration/agent-config#woodpecker_max_procs"
           >
-            <span class="text-color-alt">The max amount of parallel pipelines executed by this agent.</span>
+            <span class="text-color-alt">{{ $t('admin.settings.agents.capacity.desc') }}</span>
             <TextField :model-value="selectedAgent.capacity?.toString()" disabled />
           </InputField>
 
@@ -98,11 +98,15 @@
           </InputField>
         </template>
 
-        <Button
-          :is-loading="isSaving"
-          type="submit"
-          :text="isEditingAgent ? $t('admin.settings.agents.save') : $t('admin.settings.agents.add')"
-        />
+        <div class="flex gap-2">
+          <Button type="button" color="gray" :text="$t('cancel')" @click="selectedAgent = undefined" />
+          <Button
+            :is-loading="isSaving"
+            type="submit"
+            color="green"
+            :text="isEditingAgent ? $t('admin.settings.agents.save') : $t('admin.settings.agents.add')"
+          />
+        </div>
       </form>
     </div>
   </Panel>