chore: lint cleanup and version corrections

- Accept benign linter changes (version notes, explicit tags, formatting)
- Fix incorrect version downgrades introduced by linter:
  - golang:1.22→1.26 (restored)
  - rust:1.82→1.95 (restored)
- 23 files updated

21_case_devops/21.1_devops_workflow.md

@@ -30,7 +30,7 @@ RUN go build -o main .
 
 ## Final stage
 
-FROM alpine:latest
+FROM alpine:3.21
 WORKDIR /app
 COPY --from=builder /app/main .
 CMD ["./main"]