[Deprecation] Legacy Routes Service (`legacy-routes`)

[silug]

Summary

Legacy 3.x compatibility routing is still implemented via dedicated legacy-routes service and adapter logic. Comments indicate this compatibility is intended to be removed.

Why This Is Soft / Inferred

No single explicit runtime deprecation warning is emitted for the service itself, but code comments repeatedly frame it as a temporary compatibility hack.

Evidence

• src/clj/puppetlabs/services/master/master_service.clj:182 comment says old route-config hack can be removed when legacy routes are removed.
• src/clj/puppetlabs/services/master/master_core.clj:1315 comment repeats removal condition for legacy routes support.
• src/clj/puppetlabs/services/legacy_routes/legacy_routes_service.clj implements dedicated legacy routing service for compatibility endpoints.

Proposed Plan

• OpenVox Server 9:
  • Add explicit startup warning when legacy-routes service is enabled.
  • Publish migration guidance to modern routes only.
• Next major release:
  • Remove legacy-routes service and compatibility route rewrites.

Compatibility / Risk

• High risk for older/legacy agent traffic still requiring v3/legacy path behavior.
• Requires compatibility matrix validation before final removal.

Implementation Notes

• Instrument legacy-route hit counts to assess real usage before hard removal.
• Coordinate with agent support policy.

Acceptance Criteria

• OpenVox Server 9 emits explicit deprecation signal when legacy routes are active.
• Removal target and timeline are documented.
• Follow-up major release issue is created for actual deletion.

Suggested Tests

• Startup/logging tests for deprecation warning.
• Route compatibility tests retained in 9; removal tests in next major.

[silug]

Marked deprecated in comments in 13c447e (possibly elsewhere).