feat(skills): add create-issue slash-command skill (#165)

* feat(skills): add 8 new Claude Code slash-command skills

- add-translation: guide for i18n keys with MiniMessage <arg:N> enforcement
- create-service: sealed-interface + DefaultImpl + JUnit 5 test pattern
- create-phase: Minestom phase lifecycle with GamePhaseFactory wiring
- create-repository: Hibernate repository with ManisGame sealed-interface pattern
- create-adapter: Gson JsonDeserializer following adapter subpackage convention
- health-check: combined build + test + ArchUnit + import isolation report
- db-start: MariaDB Docker Compose start with health check and connection info
- create-pr: GitHub PR creation targeting master with project PR template

* fix(skills): enforce English PR body and fix base branch to main in create-pr skill

* feat(skills): add labels, milestone, project and issue reference steps to create-pr skill

* feat(skills): add create-issue slash-command skill

Adds /create-issue skill that guides creation of GitHub issues with
Conventional Commits titles, duplicate detection, label mapping,
milestone assignment, and automatic Voyager Roadmap project linking.

Author: TheMeinerLP

.claude/skills/create-issue.md

@@ -0,0 +1,107 @@
+---
+name: create-issue
+description: Create a GitHub issue with Conventional Commits title, labels, milestone, duplicate check, and Voyager Roadmap project assignment.
+---
+
+# Create Issue
+
+Create a new GitHub issue for the OneLiteFeatherNET/Voyager repository with proper labels, milestone, duplicate detection, and automatic assignment to the Voyager Roadmap project.
+
+## Rules
+
+- Issue title MUST follow Conventional Commits: `type(scope): short description` (e.g. `feat(server): add boost ring effect`).
+- Issue body MUST be written in **English** — never German.
+- Always check for duplicate issues before creating.
+- Always add the issue to the Voyager Roadmap project (ID 19) after creation.
+- A priority label (P0, P1, or P2) MUST always be assigned.
+- Labels are always fetched live from the repo before applying.
+
+## Steps
+
+1. Ask the user for the following information via `AskUserQuestion`. Collect all inputs before proceeding:
+
+   - **Title** — must follow Conventional Commits: `type(scope): short description`
+   - **Body / description** — what the problem or feature request is, and what the acceptance criteria are
+   - **Commit type** — one of `feat`, `fix`, `docs`, `chore`, `ci`, `refactor`, `test`
+   - **Domain label(s)** — any of: `gameplay`, `database`, `infrastructure`, `setup` (optional, pick all that apply)
+   - **Priority** — one of `P0` (critical), `P1` (high), `P2` (normal)
+   - **Milestone** — pick from the list below (by number):
+     - 1 — Sprint 1: Playable Loop
+     - 2 — Sprint 2: Complete Cup Flow
+     - 3 — Alpha v0.1
+     - 4 — Beta v0.2
+     - 5 — Release v1.0
+
+2. Validate the title format. It must match the pattern `type(scope): short description`. Valid types are: `feat`, `fix`, `docs`, `chore`, `ci`, `refactor`, `test`. If the title does not match, tell the user the correct format and ask them to correct it before continuing.
+
+3. Check for duplicate issues. Extract two or three keywords from the issue title and search open issues:
+```bash
+gh issue list --repo OneLiteFeatherNET/Voyager --state open --search "<keywords from title>"
+```
+If results are returned, list them (number, title, URL) and ask the user:
+- "These open issues may be related. Do you want to proceed with creating a new issue, or would you like to use one of the existing ones instead?"
+- Only continue if the user confirms creation.
+
+4. Fetch available labels from the repo:
+```bash
+gh label list --repo OneLiteFeatherNET/Voyager
+```
+
+5. Map the commit type to a primary label:
+   - `feat` → `enhancement`
+   - `fix` → `bug`
+   - `docs` → `documentation`
+   - `chore` → `chore`
+   - `ci` → `ci`
+   - `refactor` → `cleanup`
+   - `test` → `testing`
+
+   Combine with domain labels chosen in step 1, the priority label (P0/P1/P2), and any other applicable labels from the fetched list (e.g. `sprint-1`, `sprint-2`, `blocked`, `breaking`).
+
+6. Compose the issue body using the following template (fill in all sections in English):
+
+```
+## Problem / Feature
+
+<!-- Describe the problem or feature request -->
+
+## Acceptance Criteria
+
+- [ ] ...
+
+## Additional Context
+
+<!-- Screenshots, logs, related issues, etc. -->
+```
+
+Replace the placeholder comments with the content the user provided in step 1. Keep acceptance criteria as checkboxes (`- [ ] ...`).
+
+7. Create the issue:
+```bash
+gh issue create \
+  --repo OneLiteFeatherNET/Voyager \
+  --title "<type(scope): short description>" \
+  --body "<full body from step 6>" \
+  --label "<label1>,<label2>,..." \
+  --milestone "<milestone title>"
+```
+
+Capture the issue URL returned by the command.
+
+8. Add the issue to the Voyager Roadmap project (project ID 19):
+```bash
+gh project item-add 19 --owner OneLiteFeatherNET --url "<issue-url>"
+```
+
+9. Display the final issue URL and a summary:
+   - Issue URL
+   - Labels applied
+   - Milestone assigned
+   - Confirmation that the issue was added to the Voyager Roadmap project
+   - Confirmation that no duplicate was found (or that the user confirmed despite a potential duplicate)
+
+## Output
+
+- The URL of the newly created issue.
+- Labels, milestone, and project assignment confirmed.
+- Duplicate check result (none found, or user confirmed).