docs(adr): Update ADR 0001 - Authorization Middleware Implementation Status

[vairav]

Summary

• Updates ADR 0001 (Data Authorization Middleware) with current implementation status
• Changes status from "Proposed" to "Implemented"
• Adds implementation details for the transparent proxy architecture

Changes

• Updated status metadata to reflect implemented state
• Added implementation details section documenting the actual architecture
• Documented the proxy-based approach with OPA policy integration
• Added references to companion ADRs (0002, 0003)

Test Plan

• Verify documentation renders correctly in Sphinx
• Review technical accuracy against implemented code
• Confirm cross-references to other RFCs are valid

[MikeNeilson]

Please move the files to the "decisions" directory, see https://github.com/USACE/cwms-data-api/tree/develop/docs/source/decisions, also start from file number 0005.