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-transitions.puml

@@ -0,0 +1,113 @@
+@startuml
+package "core:transitions" {
+  data class WorkflowGraph {
+    + id: String
+    + stages: Map
+    + transitions: Set
+    + start: StageId
+  }
+
+  data class StageConfig {
+    + requiredCapabilities
+    + tokenBudget
+    + generationConfig
+    + allowedTools
+    + produces
+  }
+
+  data class TransitionEdge {
+    + id: TransitionId
+    + from: StageId
+    + to: StageId
+    + condition: TransitionCondition
+  }
+
+  fun interface TransitionCondition {
+    + evaluate(EvaluationContext): Boolean
+  }
+
+  interface TransitionResolver {
+    + resolve(WorkflowGraph, EvaluationContext): TransitionDecision
+  }
+
+  class DefaultTransitionResolver
+
+  sealed interface TransitionDecision {
+    data class Move
+    data object Stay
+    data class Blocked
+    data object NoMatch
+  }
+
+  data class EvaluationContext {
+    + sessionId
+    + currentStage
+    + artifacts
+    + variables
+  }
+
+  fun interface TransitionConditionEvaluator
+  fun interface PromptResolver
+
+  interface StageExecutor
+  interface StageExecutionEventMapper
+
+  data class StageExecutionRequest
+  sealed interface StageExecutionResult {
+    data class Success
+    data class Failure
+  }
+
+  DefaultTransitionResolver ..|> TransitionResolver
+  DefaultTransitionResolver --> TransitionConditionEvaluator
+  DefaultTransitionResolver --> TransitionOrdering
+
+  WorkflowGraph *-- StageConfig
+  WorkflowGraph *-- TransitionEdge
+  TransitionEdge *-- TransitionCondition
+
+  TransitionResolver --> TransitionDecision
+  TransitionResolver --> EvaluationContext
+
+  StageExecutionEventMapper --> StageExecutionRequest
+  StageExecutionEventMapper --> StageExecutionResult
+  StageExecutionEventMapper --> EventPayload
+
+  package "conditions" {
+    class AlwaysTrue
+    class VariableEquals
+    class ArtifactPresent
+    class ArtifactAbsent
+    class ArtifactValidated
+    class AllOf
+    class AnyOf
+    class Not
+  }
+
+  AlwaysTrue ..|> TransitionCondition
+  VariableEquals ..|> TransitionCondition
+  ArtifactPresent ..|> TransitionCondition
+  AllOf ..|> TransitionCondition
+
+  package "cycle detection" {
+    class CycleExtractor
+    class CycleDfs
+    class DeterministicAdjacencyBuilder
+    object CycleCanonicalizer
+    data class DetectedCycle
+  }
+
+  package "cycle policy" {
+    sealed interface CyclePolicy {
+      data class Retry
+      data class Refinement
+      data class Approval
+    }
+    data class CycleSignature
+    data class CyclePolicyBinding
+    class CyclePolicyResolver
+    class PolicyValidation
+  }
+}
+
+@enduml