fix(deps): add pip-tools lockfile with hash pinning — VC-53681

Introduces requirements.in and requirements-build.in as pip-tools source
manifests. requirements.txt and requirements-build.txt are now fully
hash-pinned lockfiles generated with pip-compile --generate-hashes,
covering all transitive dependencies with SHA-256 hashes.

Generated using Python 3.9 to ensure compatibility with the project's
supported Python versions (3.9, 3.10). No package versions were changed —
this purely adds auditability of transitive dependencies.

Author: ndevarapalli-panw

requirements-build.in

@@ -0,0 +1,4 @@
+pytest==7.4.3
+pytest-cov==4.1.0
+safety==2.3.5
+bandit==1.7.7