Add auth-fake-executor profile for local development

[nikola-jokic]

What type of PR is this?

Dev experience

What this PR does / why we need it

makes it easier to test job transformations without running executor while still having auth logic.

[greptile-apps]

Greptile Summary

The PR adds an authenticated fake-executor profile for exercising authenticated local job flows without Kubernetes.

• Adds the auth-fake-executor Goreman Procfile.
• Connects the profile to the auth Compose dependencies and Keycloak readiness check.
• Documents the new profile in the local-development guides.

Confidence Score: 4/5

The PR is not yet safe to merge because its documented auth-fake-executor -dap invocation fails before startup.

The current profile-selection logic appends -dap and requires _local/procfiles/auth-fake-executor-dap.Procfile, but this PR does not add that file, so the previously reported startup failure remains.

Files Needing Attention: magefiles/dev.go, _local/procfiles/auth-fake-executor-dap.Procfile

Important Files Changed

Filename	Overview
magefiles/dev.go	Adds profile selection, auth dependency startup, and Keycloak readiness handling; the existing DAP selection path still targets a missing profile variant.
_local/procfiles/auth-fake-executor.Procfile	Defines the authenticated local service set using the fake executor instead of the Kubernetes executor.
docs/developer_guide.md	Documents selection and behavior of the authenticated fake-executor profile.
_local/README.md	Adds the new profile to the local Procfile inventory, although its claim that every listed profile has a DAP variant is not yet satisfied.

_{Reviews (4): Last reviewed commit: "wip" | Re-trigger Greptile}