feat(prowler): chunk13 add the GCP service routes (#422)

[Christophe Melchior (Kakudou)]

Part of #422.

Chunk 13 of the Prowler injector stack: add the GCP service routes — the CHK.013 GCP service assessment: the BDD suite (behaviour, OCSF status / lifecycle logs / verbose diagnostics / OCSF capture fixtures), the GCP service routes in contracts/gcp.py with the shared service-contract execution refactored across all provider contracts in this chunk, the _core/prowler_client/ wiring, their registration in the registry / __init__, the formatting pass over the three service-contract BDD suites (chk011, chk012, chk013), and the cross-chunk BDD updates (chk001, chk007, chk008, chk009, chk010) plus the chk006 unit registry expectations.

Re-landed from feat/422-prowler-chk013-service-gcp-assessment (c380314..888d5a3): 9 source commits folded into 4 (N1: f7e1416; N2: 722fd87 + 40fe009 + f7b8077 + f08a940 + 888d5a3; N3: 25217d6, retitled; N4: aa375d5 + 69d8d20). N2 landed at the source-final post-image of the CHK.013 BDD suite, so the four later alignment commits folded in as content with zero conflicts; N3 is the standalone formatting pass over the three service BDD suites, and because chk013's own formatting was already carried by N2's final post-image, N3's observable diff is the chk011/chk012 suites. Gate V (whole-branch tree vs source tip 888d5a3): byte-identical except (a) the 14 pyproject.toml version differences of the other injectors (source base 3.260805.0 vs re-land base 3.260821.0; prowler/ subtree untouched), (b) the 10 trap-analysis.md files (chk004–chk013) excluded by standing call, and (c) one approved deviation — the pinned pyoaev version assert removed from prowler/tests/unit/chk006_executable_base/test_outputs_registry_runtime.py.