Fix critical Azure VMSS zero-scale bugs (timing, race conditions, SQL) (kevoreilly#2905)

* Fix case-sensitive platform comparison in Azure VMSS

Platform comparison was case-sensitive, causing tasks to fail when
platform tag used different casing (e.g., 'Windows' vs 'windows').

Fix: Use .lower() on both sides of comparison.

File: modules/machinery/az.py
Lines: ~660

* Fix SQL NULL handling in options_not_like filter

Tasks with NULL or empty 'options' were not scheduled because
SQL 'NULL NOT LIKE x' returns NULL (not TRUE).

Fix: Import or_() and explicitly check for NULL and empty string.

File: lib/cuckoo/core/database.py
Lines: ~58 (import), ~2100 (fix)

* Fix 7 critical Azure VMSS zero-scale bugs

This commit combines 7 interdependent fixes for az.py:

1. VM provisioning timing (retry loop: 12×5s)
2. Scaling-flag race condition (add scaling_lock)
3. Import TASK_RUNNING for task counting
4. VMs deleted while tasks running (count PENDING+RUNNING)
5. Scaling flag deadlock (finally block)
6. Placeholder duplicate key (session.flush)
7. Zero-scale placeholder check (machine.reserved)

All fixes tested together in production for 2 weeks.

File: modules/machinery/az.py
Lines: Multiple locations (~26, ~96, ~444, ~641, ~687, ~1126, ~1381)

Author: xtarget

lib/cuckoo/core/database.py

@@ -56,6 +56,7 @@
         # event,
         func,
         not_,
+        or_,
         select,
         Select,
         delete,
@@ -2097,7 +2098,15 @@ def list_tasks(
         if options_like:
             stmt = stmt.where(Task.options.like(f"%{options_like.replace('*', '%')}%"))
         if options_not_like:
-            stmt = stmt.where(Task.options.notlike(f"%{options_not_like.replace('*', '%')}%"))
+            # Fix: SQL NULL NOT LIKE returns NULL, not TRUE
+            # Must explicitly check for NULL and empty string
+            stmt = stmt.where(
+                or_(
+                    Task.options is None,
+                    Task.options == "",
+                    not_(Task.options.like(f"%{options_not_like.replace('*', '%')}%"))
+                )
+            )
         if tags_tasks_like:
             stmt = stmt.where(Task.tags_tasks.like(f"%{tags_tasks_like}%"))
         if task_ids: