feat(workflow): orchestrate resumable dataflow handoffs

docs/CONCEPT.md

@@ -104,19 +104,23 @@ The first executable slice now provides:
 - trigger, activity, review, decision, wait, module-action, Dataflow, and outcome
   nodes
 - API discovery and validation endpoints
+- revision-pinned, idempotent Workflow instances
+- persisted steps and append-only transition evidence
+- durable Dataflow handoff, progress reconciliation, output references,
+  retries, cancellation, and warning/review paths
+- manual activity, review, and wait handoffs with comments and evidence
+- a worker capability with current-authorization rechecks
+- an operator dialog for starting, inspecting, and advancing instances
 
 The next execution slices should provide:
 
 - static workflow definition registration from configuration packages
-- create/read/list workflow instances
-- transition execution with permission checks
+- event, API, schedule, and parent-workflow start dispatchers
 - guard hooks implemented through capability calls
-- command execution records with retry/manual-resolution state
+- registry-driven generic module-action execution records
 - action/effect previews for transitions that call other modules
-- idempotency keys for command execution
 - explicit blocked, retryable, quarantined, manual-required, and
   compensation-required states
-- basic WebUI instance detail and definition viewer
 - dashboard summary provider
 - event emission and audit integration
 
@@ -149,12 +153,16 @@ details.
 
 ## Data Model Sketch
 
-Candidate tables:
+Current tables:
 
 - `workflow_definitions`
-- `workflow_definition_versions`
+- `workflow_definition_revisions`
 - `workflow_instances`
-- `workflow_transition_history`
+- `workflow_instance_steps`
+- `workflow_instance_events`
+
+Future generic action execution and timers may add:
+
 - `workflow_command_records`
 - `workflow_timers`
 
@@ -163,16 +171,14 @@ reference the exact version used at start.
 
 ## WebUI
 
-Initial route contributions:
+Current route contribution:
 
 - `/workflow`
-- `/workflow/instances/:instanceId`
-- `/workflow/definitions/:definitionId`
 
-The UI should show current state, available transitions, pending commands,
-failed handoffs, audit trace, and linked subject records. It should not import
-case/task/template components directly; panels are contributed through core UI
-extension points.
+The route combines the definition editor and a fixed run dialog showing current
+state, available transitions, failed handoffs, comments/evidence, immutable
+event history, and linked Dataflow results. It does not import Dataflow or other
+domain UI components.
 
 ## Tests