Phase 8: CSV + ICS export, print view, MkDocs docs, SBOM + dev-mode auth

Auth (Test-Mode):
  - middleware.AuthMiddleware now takes a devMode flag. In dev,
    requests without Authorization fall back to a deterministic dev
    UUID (00000000-...-001) and role=teacher. ENVIRONMENT=production
    re-enables the strict 401 path.
  - main.go wires devMode = cfg.Environment != "production".
  - page.tsx replaces the red 'Anmeldung noch nicht integriert' banner
    with a softer Testumgebung notice; the manual-token form moves
    behind a nested details block.

Export endpoints (school-service):
  - LoadExportLessons joins tt_lesson with tt_period for wall-clock
    times; one query feeds both CSV and ICS.
  - WriteCSV streams 10 columns including pinned flag.
  - WriteICS emits one VEVENT per lesson anchored to a Monday — caller
    overridable via ?start=YYYY-MM-DD. RFC 5545 escapes for ',', ';',
    '\n' in icsEscape().
  - NextMonday helper for the default anchor.
  - GET /timetable/solutions/:id/export.{csv,ics} handlers attach
    Content-Disposition: attachment so browsers download instead of
    rendering.

Frontend:
  - lib/stundenplan/api.ts downloadSolutionExport() fetches as blob,
    triggers a synthetic <a download> click, and forwards the JWT when
    present.
  - PlanView gains CSV / ICS / Drucken buttons next to the perspective
    selector. The toolbar carries class 'no-print' so window.print()
    yields only the grid.
  - globals.css @media print rule hides chrome, forces white
    background, gives the table proper borders for A4.

Docs:
  - docs-src/services/stundenplan/{index,architecture,constraints,
    solver-tuning,export}.md with nav entry in mkdocs.yml under
    Services → Stundenplaner.
  - sbom/stundenplan/README.md lists manually-verified key dependencies
    and the policy reference. scripts/stundenplan-sbom.sh generates
    full machine-readable inventories via go-licenses + pip-licenses
    + license-checker when those tools are available.

Tests:
  - internal/services/timetable_exports_test.go: 4 unit tests covering
    CSV column layout + quoting, ICS structure + DTSTART formatting,
    icsEscape special chars, NextMonday weekday math.
  - studio-v2/e2e/stundenplan-export.spec.ts split out of the main spec
    file (LOC budget) — 3 tests for button render, CSV download,
    ICS download.
  - mockSchoolApi extended with export.csv + export.ics routes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

school-service/internal/middleware/middleware.go

@@ -104,11 +104,28 @@ func RateLimiter() gin.HandlerFunc {
 	}
 }
 
-// AuthMiddleware validates JWT tokens
-func AuthMiddleware(jwtSecret string) gin.HandlerFunc {
+// devUserID is the deterministic UUID injected when AuthMiddleware runs in
+// development mode without a JWT. It's the all-zero UUID's first byte set so
+// constraint-ownership filters can still match rows created by the dev user.
+const devUserID = "00000000-0000-0000-0000-000000000001"
+
+// AuthMiddleware validates JWT tokens.
+//
+// devMode=true relaxes the check: requests without an Authorization header
+// fall back to a fixed dev user instead of being rejected. Useful for
+// studio-v2 against a local school-service when no real login is wired up.
+// In production (devMode=false) the original strict behaviour applies.
+func AuthMiddleware(jwtSecret string, devMode bool) gin.HandlerFunc {
 	return func(c *gin.Context) {
 		authHeader := c.GetHeader("Authorization")
 		if authHeader == "" {
+			if devMode {
+				c.Set("user_id", devUserID)
+				c.Set("email", "dev@breakpilot.local")
+				c.Set("role", "teacher")
+				c.Next()
+				return
+			}
 			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
 				"error": "Authorization header required",
 			})