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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.claude/skills/artifact/references/RC.md

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+# SQA Review Record (RC)
+
+One record per review of a specific artifact instance against its QC
+checklist. Create one for **every** artifact instance in the project.
+
+- **File:** `docs/sqa/reviews/rc-<NNN>-<instance-slug>.md`
+- **ID:** `RC-NNN`, sequential across all artifact types (the registry's
+  Next Available Version for `RC`).
+- **Create:** `new-artifact.sh RC --file docs/sqa/reviews/rc-NNN-<slug>.md
+  --cite <INSTANCE-ID>=<instance path> --cite QC-<SHORT>-001=framework/qc/<checklist>.md`
+
+## Required sections (after Metadata / Version History)
+
+- **Artifact Under Review** — links to the instance and to the QC checklist
+  used.
+- **Checklist Results** — `# | Criterion | Status (Pass/Fail/N-A) |
+  Evidence/Notes`, one row per criterion copied from the QC checklist, in
+  the same order.
+- **Overall Verdict** — Go / Go-with-conditions / No-Go, with rationale.
+- **Action Items** — `Action | Owner | Due`. `Owner` is a stakeholder ID from
+  the project's Stakeholder Analysis, never a role name. Every `Fail` and
+  every condition gets an item.
+
+## After the review
+
+- The reviewer must not be the artifact's author (see governance).
+- Add or update the instance's row in the Traceability Matrix, including
+  this `RC-*` in "Last Reviewed".
+- On **Go**, set the reviewed artifact's latest `## Version History` row to
+  `Accepted` and the row before it to `Deprecated` (`Approved` is not a
+  status). On Go-with-conditions the status stays `Proposed` until the action
+  items are closed. If the change is refused for good, set the row to
+  `Rejected` (the earlier `Accepted` row stays).
+- Step-by-step narrative: `framework/process/review-checklist-process.md`.