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

.claude/skills/artifact/references/BPMN.md

@@ -0,0 +1,22 @@
+# BPMN Process Model (BPMN)
+
+Cite in `CrossReference` only if the instance exists (`new-artifact.sh` checks this for you):
+
+- **BC** — The stated business goal/objective the process serves
+- **SA** — Participants / lanes — cite S-IDs
+- **UCD** — Forward link: actors and goals derived from this process
+
+## Required sections (after Metadata / Version History)
+
+1. **Purpose and Business Goal** — the Business Case objective realized
+   (cite `[BC-001]`).
+2. **Participants (Pools / Lanes)** — every participant, mapped to an `SA`
+   stakeholder ID where one exists.
+3. **Process Diagram** — valid BPMN 2.0. Message flows cross pool
+   boundaries; sequence flows do not. Keep the diagram source next to the
+   document (BPMN has no native markdown form) so it stays diffable.
+4. **Element Table** — `Element | Type | Lane | Description` for every
+   event, activity and gateway. Every gateway states its type (XOR/AND/OR)
+   and its matching join.
+5. **Path Coverage** — every path runs from a start event to a defined end
+   event; no dead ends.