Add shared report rendering

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Shared reporting and PromptKit v0.20.0 implementation plan
 
-Status: implementation in progress; Stage 1 complete.
+Status: implementation in progress; Stages 1–2 complete.
 
 ## Scope, authority, and execution
 
@@ -97,6 +97,10 @@ logical values, not YAML quoting or mapping order.
 
 ## Stage 2: Writer rendering and standard text templates
 
+**Complete.** Writer rendering and reusable text templates are implemented.
+Focused rendering tests and the root workspace suite (`GOTOOLCHAIN=local go
+test ./...` with Go 1.27.0) passed.
+
 Add these public root-package contracts:
 
 - `Format` with `FormatText`, `FormatYAML`, and `FormatJSON`; its zero value means