feat: add backup CLI commands, AI correction/modifier services, and timezone-aware date display

- Add `devplace backups` CLI subcommands (list, run, prune, clear) with job enqueueing and orphan cleanup
- Introduce `BACKUPS_DIR` and `BACKUP_STAGING_DIR` config paths for backup storage
- Implement `schedule_correction` and `schedule_modification` calls in content creation, comment creation, and comment editing flows
- Add `DEFAULT_CORRECTION_PROMPT` and `DEFAULT_MODIFIER_PROMPT` config constants for AI content processing
- Document timezone-aware date display using `local_dt`/`dt_ago` Jinja globals with client-side `Intl` localization
- Update README with AI content correction/modifier support in direct messages via `@ai` inline instructions
- Add `track_action(user["uid"], "vote")` call on upvote in `apply_vote`

devplacepy/templates/_comment.html

@@ -16,7 +16,7 @@
         <div class="comment-header">
             {% set _user = item.author %}{% set _size = 32 %}{% set _size_class = "sm" %}{% include "_avatar_link.html" %}
             {% set _user = item.author %}{% set _class = "comment-author" %}{% include "_user_link.html" %}
-            <span class="comment-time">{{ item.time_ago }}</span>
+            <span class="comment-time">{{ dt_ago(item.comment.get('created_at')) if item.comment.get('created_at') else item.time_ago }}</span>
         </div>
         <div class="comment-text rendered-content" data-render data-raw="{{ item.comment['content'] }}">{{ item.comment['content'] }}</div>
         {% set attachments = item.get('attachments', []) %}