Add Pretty Table project: plan, accepted documents and code

Business Case, Stakeholder Analysis, Project Plan and milestone MIL-001
with review records RC-001 to RC-003, then the Python project: PrettyTable
Pokemon table, constants, pytest tests, pyproject.toml, Doxyfile, CI
workflow and README.

Task: MIL-001#1
Task: MIL-001#2
Task: MIL-001#3
Task: MIL-001#4
Task: MIL-001#5
Task: MIL-001#6
Task: MIL-001#7
Task: MIL-001#8

.agents/skills/artifact/templates/ERD.md

@@ -0,0 +1,53 @@
+# @TITLE@
+
+## Metadata
+| Key | Value |
+| --- | --- |
+| ID | @ID@ |
+| CrossReference | @CROSSREF@ |
+
+## Version History
+| Date | Status | Author | Reviewer | Change | Commit |
+| --- | --- | --- | --- | --- | --- |
+| @DATE@ | Proposed | @AUTHOR@ | <reviewer S-ID> | Initial version | pending |
+
+---
+
+## Purpose and Scope
+
+## Diagram
+
+```plantuml
+@startuml
+hide circle
+entity CUSTOMER {
+  * id : int <<PK>>
+  --
+  name : string
+}
+entity ORDER {
+  * id : int <<PK>>
+  --
+  * customer_id : int <<FK>>
+}
+CUSTOMER ||--o{ ORDER : places
+@enduml
+```
+
+## Entity Table
+
+### <ENTITY>
+
+| Attribute | Type | PK/FK | Nullable | Source (DCD class.attribute) |
+| --- | --- | --- | --- | --- |
+
+## Relationship Table
+
+| Entity | Cardinality | Entity | FK | Rule |
+| --- | --- | --- | --- | --- |
+
+## Normalization Notes
+
+---
+
+@LINKS@