feat: add BPMN inspection and workflow progress visuals

docs/VISUAL_MODEL.md

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+# Workflow Visual Model
+
+The Campaign review flow is the reference for runtime workflow progress:
+
+- a compact stage rail communicates order, current state, completion, warning,
+  failure, partial progress, and locks;
+- the active handoff owns the detailed controls;
+- evidence remains visible without turning every stage into a permanent card;
+- unavailable stages stay visibly unavailable while non-blocking optional
+  stages do not interrupt the connector state.
+
+Workflow now applies that language to instance progress without importing
+Campaign code. Once the state vocabulary has stabilized, the rail should move
+to Core as a generic process-stage component and Campaign should consume it.
+
+Navigation has three distinct layers:
+
+1. the platform siderail selects a module or focused View;
+2. the module workspace selects an object or definition;
+3. the workflow stage rail describes progress inside that object.
+
+A focused View or active Workflow may suppress unrelated platform and module
+navigation, but must always provide a visible escape back to the normal View.
+Modules should not add another persistent navigation tier for workflow stages.