fix(tsgen): resolve the real GraphQL endpoint per region

[naman-contentstack]

Summary

• GraphQL requests in csdx tsgen --api-type graphql reused the CDA (REST) host and a hardcoded region alias, so any non-default region got a 403 hitting a REST host with a GraphQL query.
• Adds resolveGraphqlHost to resolve the region's actual GraphQL delivery endpoint (from stored region config, falling back to a canonical endpoint lookup by region name), failing with a clear error when a region has none configured instead of silently 403ing.

Test plan

• npx jest test/unit/helper.test.ts — 35/35 passing, including new resolveGraphqlHost regression tests (AWS/AZURE/GCP × NA/EU/AU)
• npx tsc --noEmit — clean

Jira: DX-10294

🤖 Generated with Claude Code

[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues
✅	Licenses	0	0	0	0	0 issues
✅	Code Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.

[github-actions]

🔒 Security Scan Results

ℹ️ Note: Only vulnerabilities with available fixes (upgrades or patches) are counted toward thresholds.

Check Type	Count (with fixes)	Without fixes	Threshold	Result
🔴 Critical Severity	0	0	10	✅ Passed
🟠 High Severity	0	0	25	✅ Passed
🟡 Medium Severity	0	0	500	✅ Passed
🔵 Low Severity	0	0	1000	✅ Passed

⏱️ SLA Breach Summary

✅ No SLA breaches detected. All vulnerabilities are within acceptable time thresholds.

Severity	Breaches (with fixes)	Breaches (no fixes)	SLA Threshold (with/no fixes)	Status
🔴 Critical	0	0	15 / 30 days	✅ Passed
🟠 High	0	0	30 / 120 days	✅ Passed
🟡 Medium	0	0	90 / 365 days	✅ Passed
🔵 Low	0	0	180 / 365 days	✅ Passed

✅ BUILD PASSED - All security checks passed