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/infra-inference-commons.puml

@@ -0,0 +1,15 @@
+@startuml
+!theme plain
+package "infra-inference-commons" {
+  interface ModelManager
+  interface ManagedInferenceProvider
+  class ModelDescriptor
+  enum ResidencyMode
+  class ModelLoadException
+}
+interface InferenceProvider <<core:inference>>
+ManagedInferenceProvider --|> InferenceProvider
+ModelManager --> ModelDescriptor : load()
+ManagedInferenceProvider --> ModelDescriptor : load()
+ModelDescriptor --> ResidencyMode
+@enduml