fix(platform): preserve phase6 runtime profile and role parsing

[ActiveInAI]

Summary

Fixes two Phase 6 runtime guard regressions reported after PR #17.

Fixes

• Normalize INSOMEOS_PROFILE before runtime profile selection.
  • Production, PRODUCTION, and production now select production behavior.
  • Staging, STAGING, and staging keep production-like strict context behavior.
  • Production profile still rejects weak context fallback.
• Accumulate repeated roles query parameters.
  • ?roles=engineer&roles=reviewer now keeps both roles.
  • Comma-separated role lists continue to work.
  • Existing header role priority is preserved.

Validation

• cargo fmt --all -- --check
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test --all-targets --all-features
• cargo build --release --bin insomeos-gateway
• npx --yes @redocly/cli@2.30.0 lint openapi.yaml
• npx --yes @openapitools/openapi-generator-cli@2.23.0 generate -i openapi.yaml -g typescript-fetch -o /tmp/architoken-sdk-ts
• git diff --check

OpenAPI

Redocly passes with 1 existing localhost dev server warning.

Scope

Only modifies:

• 04-backend/harness-core/src/runtime_context.rs
• 04-backend/harness-core/src/bin/gateway.rs