[workshop-sim] Repair: Move the Copilot access check to the top of Write Your First Agentic Workflow

### Problem statement

`07-first-workflow` (mapped to `07-your-first-workflow.md` + `07d-confirm-model-access.md`) has the highest conditional dropout in the simulation (21.9% across 21,930 at-risk runs). Unlike the other top-dropout steps, its dominant failure category is `copilot-access-missing` (3,967 of 4,806 failures) — an access barrier tied to whether the learner's account/org actually has usable Copilot access — not a clarity problem with the instructions themselves. Semantic review confirmed the content already has strong instructional coverage: `07-your-first-workflow.md` verifies Copilot access with a test prompt *before* authoring begins (an `[!IMPORTANT]` callout at the top explicitly warns that unresolved access issues will cause Step 8 to fail), and the linked billing side quest (`side-quest-07d-billing-paths.md`) gives complete, checkpointed configure/recompile/commit steps for both organization-centralized and personal billing paths. The gap is that this verification happens only after the learner has already read through the workflow-creation walkthrough, rather than as the very first gate.

### Proposed change

Move the existing "Verify Copilot access before you begin" test-prompt check (currently under "Before You Start" partway down `07-your-first-workflow.md`) to the top of the page, immediately after the title, so a learner with an access gap is redirected to `07d-confirm-model-access.md` / the billing side quest before investing time in the frontmatter-authoring walkthrough. Keep all existing content, checklist items, and the billing side quest exactly as-is — this is a reordering/promotion change, not a content removal.

### Failure mode classification

**Access barrier** — the failure is a genuine Copilot license/org-billing configuration gap on the learner's account, which content sequencing can surface earlier but cannot eliminate outright.

### Quantitative guardrail

- Current `overall_score` for `07-your-first-workflow.md`: 6.25/10
- Weakest rubric dimension(s): `checkpoint_quality` (0.0/10 — likely a rubric-detector artifact since the page has a `## :white_check_mark: Checkpoint` section using the GitHub shortcode form; verify the shared `CHECKPOINT_RE` regex before treating this as a true gap) and `active_learning` relative to peers (6.3/10, already comparatively strong)
- Current learning KPI index: `(2.0 × 6.3 + 2.0 × 0.0 + 1.5 × 5.0) / 5.5 = 3.65/10`
- Why the proposed change should raise or hold these scores: promoting an existing verification step earlier in the page does not remove any authoring practice, frontmatter exercise, or checklist item — it only changes ordering — so `active_learning` and `scaffolding` should hold flat or improve (earlier gating is itself a scaffolding improvement), and `overall_score`/KPI index should not decrease.

### Acceptance criteria

- [ ] The shared curriculum quantitative assessment `overall_score` for `07-your-first-workflow.md` stays flat or improves after the change
- [ ] The step's learning KPI index `(2.0 × active_learning + 2.0 × checkpoint_quality + 1.5 × scaffolding) / 5.5` stays flat or improves versus the current 3.65/10 baseline
- [ ] The full workflow-authoring prompt, the compile/commit/push instructions, and all 7 existing checklist items remain present and unchanged in content
- [ ] The Copilot-access test-prompt check appears as the first actionable step on the page, before the workflow-authoring prompt

### Suggested owner

`workshop maintainer`
Related to #3447

> Generated by [🔬 Workshop Student Simulator](https://github.com/githubnext/gh-aw-workshop/actions/runs/35109821545) · copilot · auto · 164.9 AIC · ⌖ 7.67 AIC · ⊞ 15.2K · [◷](https://github.com/search?q=repo%3Agithubnext%2Fgh-aw-workshop+is%3Aissue+%22gh-aw-workflow-call-id%3A+githubnext%2Fgh-aw-workshop%2Fworkshop-student-simulator%22&type=issues)
> - [x] expires on Sep 17, 2026, 2:52 PM UTC

Open 07-your-first-workflow.md and locate the existing “Verify Copilot access before you begin” check, then review 07d-confirm-model-access.md and side-quest-07d-billing-paths.md for the linked flow. Run the shared curriculum quantitative assessment, including its CHECKPOINT_RE handling, before and after the reorder. Done means the access check is the first actionable step, all existing workflow instructions and seven checklist items remain unchanged, and the overall score and KPI index do not decrease.

Written by the indexing model from the issue text.