Fix all lint issues: Dockerfiles (DL3015/DL3013/DL4006) + Ruff (173→0 errors)

Dockerfile fixes:
- edu_master/phpsessid-bot: add --no-install-recommends, pin pip versions
- edu_master/webinar-checker: pin pip versions with --no-cache-dir
- userbot: add SHELL with pipefail for pipe operations

Ruff fixes (173 → 0):
- W293/W291/W292: whitespace clean via ruff format
- N806: camelCase → snake_case (anilist, safone, hearts, flux, etc.)
- ARG001/ARG002: prefix unused params with _
- SIM115: use context managers for file I/O
- SIM117: combine nested with statements
- S608: noqa on SQL f-strings (module name is validated)
- E402/N812/N817: import fixes
- B023: pass loop variable as argument
- I001: auto-sorted imports
- syntax: fixed = vs == in dtek_notif/main.py

userbot/utils/rentry.py

@@ -138,14 +138,14 @@ async def paste(
 
         print(f'URL: {url} - Edit Code: {edit_code} - Time: {ftime}')
 
-        rallUrls = db.get('core.rentry', 'urls', default={'allUrls': {}})
+        rall_urls = db.get('core.rentry', 'urls', default={'allUrls': {}})
         entry_id = str(uuid4())
-        rallUrls['allUrls'][entry_id] = {
+        rall_urls['allUrls'][entry_id] = {
             'url': short_url,
             'edit_code': edit_code,
             'time': ftime,
         }
-        db.set('core.rentry', 'urls', rallUrls)
+        db.set('core.rentry', 'urls', rall_urls)
 
     if return_edit:
         return (url, edit_code)
@@ -156,19 +156,19 @@ async def rentry_cleanup_job():
     """Periodically checks and deletes rentry pastes older than 24 hours"""
     while True:
         try:
-            rallUrls = db.get('core.rentry', 'urls', default={'allUrls': {}})
+            rall_urls = db.get('core.rentry', 'urls', default={'allUrls': {}})
             now = datetime.now()
             deleted_count = 0
             error_count = 0
 
-            for entry_id, entry in list(rallUrls['allUrls'].items()):
+            for entry_id, entry in list(rall_urls['allUrls'].items()):
                 url = entry['url']
                 entry_time = datetime.strptime(entry['time'], '%d %I:%M:%S %p %Y')
 
                 if now - entry_time > timedelta(days=1):
                     try:
                         delete(url, entry['edit_code'])
-                        del rallUrls['allUrls'][entry_id]
+                        del rall_urls['allUrls'][entry_id]
                         deleted_count += 1
                         print(f'[#] Deleted expired rentry paste: {url}')
                     except Exception as e:
@@ -179,7 +179,7 @@ async def rentry_cleanup_job():
                 print(f'[*] Cleanup summary: {deleted_count} deleted, {error_count} failed')
 
             if deleted_count:
-                db.set('core.rentry', 'urls', rallUrls)
+                db.set('core.rentry', 'urls', rall_urls)
 
         except Exception as e:
             print(f'[!] Error in rentry cleanup job: {str(e)}')