fix: remediate remaining audit security findings

[baixiangcpp]

Summary

• Add shared codegen literal encoders and use them in HTTP request builder and cURL-to-code outputs.
• Harden JWT claim parsing, password randomness, regex safety checks, SVG optimizer output sanitization, and Service Worker query caching.
• Add CI token read-only permissions and regression tests for the remediated audit findings.

Verification

• npm run lint
• npm run test
• npm run validate
• npm run build:app
• npm run build:post
• npm run test:e2e:smoke

Notes

• npm audit --audit-level=high currently fails on existing dependency advisories, including a high severity ws advisory through webpack-bundle-analyzer. I did not add it as a required CI gate in this PR to avoid making CI red before the dependency upgrade is handled.

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