Implement learner-record platform slice and role-aware workspace shell

[Cataldir]

Purpose

• Implement the learner-record platform slice across backend, infra, frontend, and docs.
• Add normalized access-context and learner-record projection contracts for configuration and insights services.
• Introduce hybrid learner-record publication with Cosmos as the authoritative store and Service Bus as the distribution seam.
• Reframe the frontend around role-aware workspace routes, public trust/program pages, and calmer workspace-aligned UI.
• Document the new architectural direction with ADRs and supporting brief/backlog/risk/UX artifacts.

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe:

How to Test

• Get the code

git clone https://github.com/Azure-Samples/tutor.git
cd tutor
git checkout <branch-name>

• Test the code

pytest tests/configuration/test_configuration_api.py tests/insights/test_insights_api.py
cd frontend && pnpm lint

What to Check

Verify that the following are valid

• /access-context returns normalized roles, grants, contexts, and feature flags for local-dev headers.
• Insights workspace snapshot and learner-record endpoints return the new trust/freshness/timeline shapes.
• Frontend workspace routes render role/context-aware shells without duplicate key warnings.
• Essay and workspace shell UI follow the calmer, sober design language.
• Terraform outputs include learner-record and Service Bus values required by the slice.
• ADRs and strategy docs reflect the learner-record-centered platform direction.

Other Information

• Local validation completed with targeted pytest coverage and frontend lint.
• This PR is intended to close the linked issue for the learner-record/workspace shell platform slice.