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/test-deterministic.puml

@@ -0,0 +1,21 @@
+@startuml
+package "test-deterministic" {
+  [SessionReplayDeterminismTest]
+  [ContextCompressionDeterminismTest]
+  [ApprovalEngineDeterminismTest]
+  [RouterProjectorTest]
+  [RouterFacadeTest]
+  [GraphValidatorTest]
+  [ValidationPipelineShortCircuitTest]
+  [DefaultContextPackBuilderTest]
+  [TokenBudgetEnforcementTest]
+}
+
+[SessionReplayDeterminismTest] --> [EventReplayer] : replay N times
+[ContextCompressionDeterminismTest] --> [ContextCompressor] : compress N times
+[ApprovalEngineDeterminismTest] --> [ApprovalEngine] : decide N times
+
+note right of [SessionReplayDeterminismTest]
+  assert: state == state == state
+end note
+@enduml