feat(interactive): add reflection-driven interactive prompt engine

[ben-kalmus]

Summary

• Adds pkg/interactive, a generic package that builds a request body by walking any Go struct with reflection and prompting for each field. It is the foundation for --interactive modes across the CLI.

• This PR introduces the engine only. No command is wired to it yet (see the follow-up PR adding --interactive to compositions upsert).

Demo

Stacked PRs

• feat(interactive): add reflection-driven interactive prompt engine #249 <- this PR
  • Introduces the generic interactive package
• feat(compositions): add interactive mode to compositions commands #252
  • Includes interactive as option to Compositions API commands

How it works

• Builder.Build(&v) walks the struct and prompts for inputs: optional pointer fields can be skipped, large optional-only parameter objects let you multi-select which fields to fill.

• Enums (named string types the SDK generates with an IsValid() bool method) are validated against the SDK's own check via reflection.

• Bad input does not abort the build. It re-prompts in place (non-numeric integer, malformed JSON, empty required field) using validators.

• A depth/cycle guard degrades self-referential structures to a raw-JSON prompt instead of looping forever.

Design notes

• SDK-agnostic: the package imports only pkg/iostreams and pkg/prompt, no SDK or command packages, so any command can reuse it.

• Input is gathered through a small Prompter interface (Input/Confirm/Select/MultiSelect). Production uses SurveyPrompter; tests use ScriptedPrompter, a label-keyed fake whose answers match by field label rather than call order, so tests do not break when SDK changes.

Changes

• pkg/interactive/prompter.go: Prompter interface and SurveyPrompter (survey/v2 via pkg/prompt).
• pkg/interactive/scripted_prompter.go: ScriptedPrompter, the reusable label-keyed test fake.
• pkg/interactive/builder.go: the reflection walk (scalars, optional pointers, unions, parameter bags, slices, maps, enum and input validation).
• pkg/interactive/classify.go: reflection helpers (union, parameter-bag, required-field detection).
• pkg/interactive/validators.go: input validator builders (required string, integer, number, boolean, JSON).

Tests

Unit tests under pkg/interactive covering:

• Scalars, optional pointers (set and skipped), and enums (valid and rejected)
• oneOf unions, parameter bags, slices, and map[string]string
• Pre-populated fields preserved, and the depth/cycle guards falling back to raw JSON
• Validator behavior and both the scripted and survey prompters

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 228 complexity · 9 duplication

Metric	Results
Complexity	228
Duplication	9

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