Feat v0.9.2 Starlark converter consolidation + snapshot cleanup (#75)

Consolidate duplicate Go↔Starlark converters into sandbox/convert.go
and snapshot parsers into models/snapshot.go. Standardize snapshot
creation on wrapped format. Net -393 lines across 21 files.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,44 @@
 
 All notable changes to Armature are documented here.
 
+## v0.9.2 — Starlark Converter Consolidation + Snapshot Cleanup
+
+Consolidates duplicated Go↔Starlark conversion code and snapshot
+parsers into canonical locations, removing ~350 lines of copy-paste
+across 8 files.
+
+**Converter consolidation**
+
+- New `sandbox/convert.go` with four exported functions:
+  `GoToStarlark`, `StarlarkToGo`, `DictToMap`, `MapToDict`.
+- Superset implementation handles all Go primitive types (nil, bool,
+  int, int64, float64, string), containers (map, slice), and Starlark
+  Tuple — covering every variant that previously existed.
+- Deleted duplicate converters from `workflow/automated.go`,
+  `handlers/starlark_helpers.go`, `handlers/workflow_hooks.go`,
+  `sandbox/workflow_module.go`, `sandbox/realtime_module.go`,
+  `sandbox/files_module.go`, `triggers/event.go`, `triggers/webhook.go`.
+- SQL-specific converters in `db_module.go` (error-returning, `[]byte`
+  handling) intentionally excluded — different semantics.
+
+**Snapshot parser consolidation**
+
+- New `models/snapshot.go` with `ParseSnapshotStages()` handling both
+  wrapped `{"stages":[...]}` and legacy flat `[...]` formats.
+- Deleted three identical parsers from `workflow/engine.go`,
+  `handlers/workflow_instance_handlers.go`, and
+  `handlers/workflow_assignment_handlers.go`.
+
+**Snapshot format standardization**
+
+- `workflow_packages.go` publish path now emits wrapped format,
+  matching `workflows.go`. All snapshot creation is consistent.
+
+**Tests:** 7 new converter tests with round-trip coverage. Existing
+engine, handler, and workflow tests updated and passing.
+
+---
+
 ## v0.9.1 — Server-Side Sub-Path Routing
 
 Hardens multi-surface routing so full-page refreshes on sub-paths work