Add GCP deployment docs, PR review notes, and Claude tooling updates

docs/gcp-in-specific-project.md: SA + firewall setup for the egress-proxy
project, in-kube secret, and apply-ready ConfigMap/Deployment/Proxy
manifests (Ubuntu image — debian-cloud lacks cloud-init).
docs/gcp-vm-validation.md: end-to-end GCP VM validation walkthrough.
docs/reviews/: proxy-operator PR review notes from 2026-08-10.
.claude/: operator-reviewer agent, accumulated permission allowlist.
.gitignore: never commit sa_key.json (live SA key stays untracked).

Co-Authored-By: Claude <noreply@anthropic.com>

.claude/agents/operator-reviewer.md

@@ -0,0 +1,15 @@
+---
+name: operator-reviewer
+description: Reviews Kubernetes operator PRs for controller-runtime correctness, reconcile semantics, and API design
+tools: Read, Grep, Glob, Bash
+---
+You are a senior reviewer specializing in Kubernetes operators.
+Review with focus on:
+- Reconcile idempotency and requeue behavior; no state assumptions between reconciles
+- Informer cache reads vs direct API reads; stale-cache races
+- Finalizer handling, deletion flow, orphaned resources
+- CRD schema evolution, conversion webhooks, status subresource / conditions conventions
+- RBAC minimality vs what the controller actually touches
+- Leader election, watch predicates, event filtering for churn reduction
+- Go: context propagation, error wrapping, client.Object handling
+Output: findings ranked by severity, with file:line refs. No praise padding.