[taigrr]

Summary

• Preserve double quotes and backslashes when serializing and parsing generated dotenv files.
• Decode only escaped quotes/backslashes inside double quotes; preserve unknown escape sequences and literal single-quoted content.
• Cover eight values in both managed and ignored blocks, plus single-quoted backslashes. Quote-containing cases fail on the base branch.

Validation

• go generate ./... before and after changes
• go test -race ./... (baseline and final)
• go vet ./...
• staticcheck ./...
• go build ./...
• goimports and git diff --check

No dependency changes. Multiline dotenv support is outside this focused fix.