docs(push): add pip dry-run dependency check to backend gate

.devin/workflows/push.md

@@ -17,16 +17,19 @@ Runs automated quality gates then commits and pushes. Pass a target to scope the
 ## Backend Gates (Python — nebula-os)
 
 ```bash
-# 1. Type check
+# 1. Resolve dependencies (dry-run to catch conflicts that only show in CI builds)
+pip install -r requirements.txt --dry-run
+
+# 2. Type check
 python -m mypy src/ --ignore-missing-imports
 
-# 2. Lint
+# 3. Lint
 python -m ruff check src/
 
-# 3. Fix lint auto-fixable issues
+# 4. Fix lint auto-fixable issues
 python -m ruff check src/ --fix
 
-# 4. Repeat until clean — do not proceed with errors
+# 5. Repeat until clean — do not proceed with errors
 ```
 
 Fix all errors before continuing. Do not add `# type: ignore` or `# noqa` to suppress — fix the root cause.