Document Promptkit report generation

docs/internal/promptkit-adapter.md

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+# Promptkit Adapter Internals
+
+`internal/adapters/promptkit` maps Weatherreporter's project-owned executor contract to Promptkit.
+The CLI maps `promptkit` configuration to a `PromptExecutorConfig` and constructs one executor
+per action. Promptkit dependency types do not escape the adapter.
+
+The adapter exposes exact prompt and profile inspection plus prepared execution. It maps Promptkit
+inspection values to project-owned prompt input, output-contract, profile, preparation, execution,
+validation, and optional debug values. It classifies adapter failures without copying provider secrets
+or unbounded response bodies into application errors or normal state.
+
+The app calls the executor's preparation callback before provider execution to persist safe preparation
+provenance. Completed executions are then persisted as safe execution provenance and raw generated text
+is validated by `internal/generatedtext`. The adapter does not write workspace state, render Markdown,
+choose report definitions, or send Distributor notifications.
+
+Focused tests:
+
+```sh
+go test ./internal/adapters/promptkit ./internal/cli ./internal/app
+```
+
+The public logical prompt/profile/schema contract is owned by the
+[Promptkit integration guide](../integrations/promptkit.md).