docs: add module documentation in AsciiDoc with PlantUML diagrams

Generated by per-group subagents covering all 52 modules across:
core (18), infrastructure (10), apps (5), interfaces (3),
plugins (7), testing (9)

Documentation format:
- AsciiDoc (.adoc) files in docs/modules/<group>/
- PlantUML (.puml) files in docs/diagrams/
- .adoc files reference diagrams via include:: directives

Each doc covers: purpose, responsibilities, non-responsibilities,
key types, event flow, integration points, invariants, PlantUML
diagram, known issues, and open questions.

docs/diagrams/core-events.puml

@@ -0,0 +1,114 @@
+@startuml
+package "core:events" {
+  interface EventPayload
+
+  abstract class NewEvent {
+    + metadata: EventMetadata
+    + payload: EventPayload
+  }
+
+  abstract class StoredEvent {
+    + metadata: EventMetadata
+    + sequence: Long
+    + sessionSequence: Long
+    + payload: EventPayload
+  }
+
+  class EventMetadata {
+    + eventId: EventId
+    + sessionId: SessionId
+    + timestamp: Instant
+    + schemaVersion: Int
+    + causationId: CausationId?
+    + correlationId: CorrelationId?
+  }
+
+  interface EventStore {
+    + append(NewEvent): StoredEvent
+    + read(SessionId): List<StoredEvent>
+    + subscribe(SessionId): Flow<StoredEvent>
+  }
+
+  class EventDispatcher {
+    + emit(EventPayload, SessionId, ...)
+  }
+
+  interface EventSerializer {
+    + serialize(EventPayload): String
+    + deserialize(String): EventPayload
+  }
+
+  class JsonEventSerializer
+
+  interface Projection<S> {
+    + initial(): S
+    + apply(S, StoredEvent): S
+  }
+
+  interface StateBuilder<S> {
+    + build(List<StoredEvent>): S
+  }
+
+  class DefaultStateBuilder<S>
+
+  interface EventReplayer<S> {
+    + rebuild(SessionId): S
+  }
+
+  class DefaultEventReplayer<S>
+
+  EventPayload <|.. SessionStartedEvent
+  EventPayload <|.. SessionPausedEvent
+  EventPayload <|.. WorkflowStartedEvent
+  EventPayload <|.. WorkflowCompletedEvent
+  EventPayload <|.. StageStartedEvent
+  EventPayload <|.. StageCompletedEvent
+  EventPayload <|.. TransitionExecutedEvent
+  EventPayload <|.. InferenceStartedEvent
+  EventPayload <|.. InferenceCompletedEvent
+  EventPayload <|.. ToolInvocationRequestedEvent
+  EventPayload <|.. ApprovalRequestedEvent
+  EventPayload <|.. ApprovalDecisionResolvedEvent
+  EventPayload <|.. ArtifactCreatedEvent
+  EventPayload <|.. ArtifactValidatedEvent
+  EventPayload <|.. RiskAssessedEvent
+  EventPayload <|.. ContextPackBuiltEvent
+  EventPayload <|.. OrchestrationPausedEvent
+  EventPayload <|.. OrchestrationResumedEvent
+  EventPayload <|.. RetryAttemptedEvent
+
+  NewEvent *-- EventMetadata
+  NewEvent *-- EventPayload
+  StoredEvent *-- EventMetadata
+  StoredEvent *-- EventPayload
+  EventDispatcher --> EventStore
+  EventDispatcher ..> NewEvent : creates
+
+  DefaultStateBuilder --> Projection
+  DefaultEventReplayer --> EventStore
+  DefaultEventReplayer --> DefaultStateBuilder
+
+  JsonEventSerializer ..|> EventSerializer
+  JsonEventSerializer --> eventJson
+
+  note right of EventPayload : 35+ concrete subtypes\nregistered in polymorphic block
+}
+
+package "shared types" {
+  value class TypeId
+  enum Tier
+  enum RiskLevel
+  enum RiskAction
+  sealed interface ApprovalStatus
+  enum ApprovalOutcome
+  sealed interface GrantScope
+  data class RetryPolicy
+  data class TokenUsage
+}
+
+TypeId <|.. SessionId
+TypeId <|.. StageId
+TypeId <|.. EventId
+TypeId <|.. ArtifactId
+
+@enduml