Add planning baseline: BC, SA, PP and two gateways

Create the Business Case, Stakeholder Analysis (S01 course participant,
S02 Udemy coursists, S03 GitHub viewers), Project Plan and the milestone
documents MIL-001 (project setup, 6 tasks) and MIL-002 (game
implementation, 8 tasks) for the console Blackjack game.

Register PP and MIL in the artifact registry, set the PO language to en,
and link the synced Gitea milestones in the Gateway Schedule.

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.agents/skills/artifact/references/GOV.md

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+# Governance / ARB Workflow (GOV)
+
+One per project: `docs/sqa/governance.md`. Sections: Purpose, ARB Review
+Workflow (submission → QC review → `RC-*` record → Go/No-Go → sign-off →
+Traceability update), RACI by Artifact Category, Escalation Rules, Cadence.
+The template has the standard text; fill the RACI.
+
+**RACI cells use exact stakeholder IDs from the project's Stakeholder
+Analysis (`S<NN>`), never role names.**
+
+Related singletons (edit the existing file, no scaffold needed):
+- `PRC` — `framework/process/review-checklist-process.md`, the narrative
+  review procedure. Framework-level; do not add project data.
+- `CSG` — `docs/sqa/coding-standards-governance.md`. Scope is *defining and
+  governing* (not enforcing) language standards and style guides, as set by
+  the project Business Case's scope.