Feat v0.3.0 workflow schema (#14)

Co-authored-by: Jeffrey Smith <jasafpro@gmail.com>
Co-committed-by: Jeffrey Smith <jasafpro@gmail.com>

CHANGELOG.md

@@ -2,6 +2,43 @@
 
 All notable changes to Switchboard Core are documented here.
 
+## v0.3.0 — Workflow Schema Redesign
+
+### Changed
+
+- **`workflow_stages` schema modernized**: Dropped chat-era columns (`persona_id`,
+  `history_mode`). Renamed `transition_rules` → `stage_config`. Updated
+  `stage_mode` CHECK from `(form_only, form_chat, review, custom)` to
+  `(form, review, delegated, automated)`.
+- **New stage fields**: Added `audience` (team | public | system), `stage_type`
+  (simple | dynamic | automated), `starlark_hook` (package_id:entry_point),
+  and `branch_rules` (JSONB array of routing conditions).
+- **Routing engine**: `ResolveNextStage` now reads `branch_rules` (flat array)
+  instead of `transition_rules.conditions` (nested object). Cleaner separation
+  between routing rules and stage config.
+- **Hook handler**: `FireOnAdvanceHook` reads from `stage_config` instead of
+  `transition_rules`. Renamed `channelID` parameter to `instanceID`.
+- **Stage CRUD validation**: New fields validated on create/update. `delegated`
+  mode requires `surface_pkg_id`. `dynamic`/`automated` stage_type requires
+  `starlark_hook`.
+- **Package export/import**: Updated to use new field names. Workflow packages
+  now include `audience`, `stage_type`, `starlark_hook`, `branch_rules`,
+  `stage_config`.
+- **Starlark workflow module**: Stage dicts now include `audience` and
+  `stage_type` keys. Removed `history_mode` and `persona_id`.
+- **Frontend stage editor**: Both admin and team-admin surfaces updated with
+  new mode values, audience selector, stage type selector, and conditional
+  Starlark hook input. Fixed pre-existing bug in admin workflows.js where
+  `STAGE_MODES` still contained `chat_only`.
+
+### Removed
+
+- `persona_id` column from `workflow_stages` (personas are extension concerns)
+- `history_mode` column from `workflow_stages` (chat-era context management)
+- `StageModeCustom`, `StageModeFormOnly`, `StageModeFormChat` Go constants
+
+---
+
 ## v0.2.9 — Builtin Extension Retirement
 
 ### Changed