feat(student): add curriculum dashboard and lab launch/reset/recreate flow

StudentDashboard.jsx — "Up Next" curriculum view + Launch Lab flow, in one
component since they share state (environment status affects what curriculum
actions make sense).

- Renders GET /api/curriculum/path as-is: the existing RootNode path
  (Foundation -> Workloads -> Networking -> Configuration -> Troubleshooting
  -> Real Ops -> Capstone), no new structure invented. Capstone stays the
  locked placeholder from the earlier slice.
- Launch Lab -> POST /api/environment/launch, polls status every 2.5s while
  provisioning/resetting, transitions through none -> provisioning -> running
  -> error with a distinct UI state for each (EnvironmentPanel). On running,
  navigates to launch_path with the student's own id as ?sid= — a
  defense-in-depth ownership check the Gateway verifies on that specific
  navigation (see the gateway commit).
- One "Recreate Lab" control, calling POST /api/environment/reset — no raw
  destroy-without-recreate exposed to students, matching "don't expose raw
  destroy/admin controls beyond what is safe for a student." A visible note
  states progress is saved separately and survives.

Platform.module.css reuses the existing design tokens from index.css
(--green, --surface, --text, etc.) so this reads as the same product as the
Lab UI, not a bolted-on separate app.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

frontend/src/platform/Platform.module.css

@@ -0,0 +1,161 @@
+/* Platform Shell styling — reuses the existing design tokens from index.css (--bg, --surface,
+   --green, --text, etc.) so the entry/dashboard screens feel like the same product as the Lab
+   UI, not a bolted-on separate app. */
+
+.entryWrap {
+  height: 100vh;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: var(--bg);
+  font-family: var(--sans);
+  color: var(--text);
+}
+
+.entryCard {
+  width: 380px;
+  background: var(--surface);
+  border: 1px solid var(--border);
+  border-radius: var(--radius-lg);
+  padding: 2rem;
+}
+
+.brand {
+  font-family: var(--mono);
+  font-size: 1.3rem;
+  font-weight: 600;
+  color: var(--green);
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+.brandIcon { font-size: 1.4rem; }
+
+.tagline { color: var(--text-2); margin: 0.5rem 0 0.25rem; font-size: 0.9rem; }
+.pilotNote { color: var(--text-3); font-size: 0.75rem; margin-bottom: 1.25rem; }
+
+.label { display: block; font-size: 0.8rem; color: var(--text-2); margin: 0.9rem 0 0.3rem; }
+
+.select {
+  width: 100%;
+  padding: 0.55rem 0.6rem;
+  background: var(--surface2);
+  border: 1px solid var(--border2);
+  border-radius: var(--radius);
+  color: var(--text);
+  font-family: var(--sans);
+  font-size: 0.9rem;
+}
+
+.primaryBtn {
+  margin-top: 1.25rem;
+  width: 100%;
+  padding: 0.65rem 1rem;
+  background: var(--green);
+  color: #05130a;
+  border: none;
+  border-radius: var(--radius);
+  font-weight: 600;
+  font-size: 0.9rem;
+  cursor: pointer;
+  text-align: center;
+  text-decoration: none;
+  display: inline-block;
+}
+.primaryBtn:disabled { opacity: 0.5; cursor: not-allowed; }
+
+.secondaryBtn {
+  padding: 0.65rem 1rem;
+  background: transparent;
+  color: var(--text);
+  border: 1px solid var(--border2);
+  border-radius: var(--radius);
+  font-size: 0.9rem;
+  cursor: pointer;
+}
+.secondaryBtn:disabled { opacity: 0.5; cursor: not-allowed; }
+
+.linkBtn {
+  background: none;
+  border: none;
+  color: var(--text-2);
+  font-size: 0.85rem;
+  cursor: pointer;
+  text-decoration: underline;
+}
+
+.errorBox {
+  background: var(--red-dim);
+  color: var(--red);
+  border: 1px solid var(--red);
+  border-radius: var(--radius);
+  padding: 0.6rem 0.8rem;
+  font-size: 0.85rem;
+  margin-bottom: 1rem;
+}
+
+/* ── Dashboard ─────────────────────────────────────────────────────────── */
+
+.dashWrap {
+  min-height: 100vh;
+  background: var(--bg);
+  color: var(--text);
+  font-family: var(--sans);
+  padding: 0 0 3rem;
+}
+
+.dashHeader {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 1.1rem 2rem;
+  border-bottom: 1px solid var(--border);
+}
+.headerRight { display: flex; align-items: center; gap: 1rem; }
+.studentName { font-weight: 600; }
+
+.card {
+  max-width: 760px;
+  margin: 1.5rem auto 0;
+  background: var(--surface);
+  border: 1px solid var(--border);
+  border-radius: var(--radius-lg);
+  padding: 1.5rem;
+}
+.card h2 { font-size: 1rem; margin-bottom: 1rem; color: var(--text); }
+
+.muted { color: var(--text-2); font-size: 0.9rem; }
+
+.stageRow { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 0.75rem; }
+.stagePill {
+  display: flex; align-items: center; gap: 0.4rem;
+  padding: 0.4rem 0.7rem;
+  background: var(--surface2);
+  border: 1px solid var(--border2);
+  border-radius: 999px;
+  font-size: 0.8rem;
+  color: var(--text-2);
+}
+.stagePillActive { border-color: var(--green); color: var(--text); }
+.stagePillLocked { opacity: 0.5; }
+.stageCount { color: var(--text-3); font-family: var(--mono); font-size: 0.75rem; }
+
+.nextUp { font-size: 0.9rem; color: var(--text); }
+
+.statusLine { display: flex; align-items: center; gap: 0.5rem; font-size: 0.9rem; margin-bottom: 0.9rem; }
+.btnRow { display: flex; gap: 0.75rem; }
+.hint { color: var(--text-3); font-size: 0.78rem; margin-top: 0.75rem; }
+
+.dotOk, .dotErr { width: 8px; height: 8px; border-radius: 50%; display: inline-block; }
+.dotOk { background: var(--green); }
+.dotErr { background: var(--red); }
+
+.spinner {
+  width: 12px; height: 12px;
+  border: 2px solid var(--border2);
+  border-top-color: var(--green);
+  border-radius: 50%;
+  display: inline-block;
+  animation: spin 0.7s linear infinite;
+}
+@keyframes spin { to { transform: rotate(360deg); } }