fix: route Base Std sync through current B20 docs

[soheimam]

Summary

• run the Base Std sync workflow jobs on BaseRunnerGroup for internal LLM Gateway access
• route every Base Std B20 source change to the current B20 reference tree and the B20 overview, payments, and launch guides
• remove retired Beryl/Cobalt targets and update the manual-update allowlist
• add routing coverage for the complete current B20 documentation set

Validation

• npm --prefix scripts run test:base-std-sync
• workflow YAML parse
• route-table JSON validation
• git diff --check

Follow-up

The LLM Gateway secret/hostname configuration remains operational configuration; this change moves the workflow off GitHub-hosted runners and onto BaseRunnerGroup.

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1