UN-2813 [FIX] Sanitize CLI queue list to prevent invalid queue names

Fix bug where malformed --queues input causes worker to crash.

**Problem:**
CLI queue list was returned without sanitization, allowing invalid
queue names to reach Celery/Temporal and crash the worker:

Examples of problematic input:
- `--queues foo,` → ["foo", ""] (empty string)
- `--queues foo, bar` → ["foo", " bar"] (whitespace)
- `--queues ,,,` → ["", "", ""] (all empty)

**Inconsistency:**
Environment variable TASK_QUEUES was properly sanitized (line 97),
but CLI --queues was not (line 88-90), creating inconsistent behavior.

**Solution:**
Apply same sanitization to CLI queues as env queues:
```python
queues = [q.strip() for q in cli_queues if q and q.strip()]
if not queues:
    raise ValueError("No queues specified via --queues after trimming...")
```

**Changes:**
1. ✅ Strip whitespace from each queue name
2. ✅ Filter out empty/whitespace-only entries
3. ✅ Validate at least one valid queue remains
4. ✅ Fail fast with clear error message

**Impact:**
- ✅ Prevents worker crashes from malformed queue input
- ✅ Consistent sanitization for CLI and env vars
- ✅ Better error messages for invalid input
- ✅ Worker starts reliably with clean queue list

**Examples:**
```bash
# Before: Crashes
--queues foo,    # → ["foo", ""]

# After: Works
--queues foo,    # → ["foo"]

# Before: Silent corruption
--queues " foo , bar "  # → [" foo ", " bar "]

# After: Clean
--queues " foo , bar "  # → ["foo", "bar"]
```

Resolves: CodeRabbit comment #2386596269
Related: #1555

Author: Deepak-Kesavan

task-backend/src/unstract/task_backend/worker.py

@@ -86,8 +86,13 @@ def _resolve_queues(self, cli_queues: list | None) -> list:
 
         # Priority 1: CLI arguments (explicit deployment)
         if cli_queues:
-            logger.info(f"Using queues from CLI arguments: {', '.join(cli_queues)}")
-            return cli_queues
+            queues = [q.strip() for q in cli_queues if q and q.strip()]
+            if not queues:
+                raise ValueError(
+                    "No queues specified via --queues after trimming empty entries."
+                )
+            logger.info(f"Using queues from CLI arguments: {', '.join(queues)}")
+            return queues
 
         # Priority 2: Environment variable (dev convenience only)
         environment = os.getenv("ENVIRONMENT", "prod").lower()