feat(plugins): scaffold git, gitea, and core plugins

Adds three new plugins to the holocron marketplace:
- git: 4 stub skills (git-commit, git-branch, git-pr, git-flow)
- gitea: 5 stub skills (gitea-issues, gitea-prs, gitea-milestones, gitea-releases, gitea-wiki)
- core: 5 stub skills (triage, diagnose, zoom-out, caveman, improve-codebase-architecture)

All plugins follow version-parity convention (ADR-0016). Skills are
placeholder stubs — content will be authored in a future workstream.
Registered in both marketplace.json paths.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/core/.claude-plugin/plugin.json

@@ -0,0 +1,18 @@
+{
+  "author": {
+    "name": "Defame1297",
+    "url": "https://git.dev.rkdr.net/Defame1297/"
+  },
+  "description": "Cross-cutting utility skills for everyday AI-assisted coding \u2014 triage, diagnosis, architecture review, and session navigation.",
+  "displayName": "Core",
+  "keywords": [
+    "cross-cutting",
+    "triage",
+    "diagnose",
+    "architecture",
+    "debug"
+  ],
+  "license": "MIT",
+  "name": "core",
+  "version": "1.0.0"
+}

plugins/core/plugin.json

@@ -0,0 +1,23 @@
+{
+  "agents": "agents/",
+  "author": {
+    "email": "defame1297@rkdr.net",
+    "name": "Defame1297"
+  },
+  "description": "Cross-cutting utility skills for everyday AI-assisted coding \u2014 triage, diagnosis, architecture review, and session navigation.",
+  "hooks": "hooks.json",
+  "keywords": [
+    "cross-cutting",
+    "triage",
+    "diagnose",
+    "architecture",
+    "debug"
+  ],
+  "license": "MIT",
+  "mcpServers": ".mcp.json",
+  "name": "core",
+  "skills": [
+    "skills/"
+  ],
+  "version": "1.0.0"
+}

plugins/core/skills/caveman/SKILL.md

@@ -0,0 +1,10 @@
+---
+name: caveman
+description: >
+  Use when you want to debug by inserting print statements and observing
+  raw output to understand program state. Stub — full content not yet written.
+metadata:
+  category: cross-cutting
+---
+
+> **Stub.** This skill is a placeholder. Content will be authored in a future workstream.

plugins/core/skills/diagnose/SKILL.md

@@ -0,0 +1,10 @@
+---
+name: diagnose
+description: >
+  Use when you want to investigate a bug, error, or unexpected behavior
+  systematically before attempting a fix. Stub — full content not yet written.
+metadata:
+  category: cross-cutting
+---
+
+> **Stub.** This skill is a placeholder. Content will be authored in a future workstream.

plugins/core/skills/improve-codebase-architecture/SKILL.md

@@ -0,0 +1,11 @@
+---
+name: improve-codebase-architecture
+description: >
+  Use when you want to identify and improve structural weaknesses in the
+  codebase architecture — coupling, cohesion, layering, or boundary violations.
+  Stub — full content not yet written.
+metadata:
+  category: cross-cutting
+---
+
+> **Stub.** This skill is a placeholder. Content will be authored in a future workstream.

plugins/core/skills/triage/SKILL.md

@@ -0,0 +1,10 @@
+---
+name: triage
+description: >
+  Use when you want to assess and prioritize a codebase problem, bug, or
+  backlog item before deciding how to act on it. Stub — full content not yet written.
+metadata:
+  category: cross-cutting
+---
+
+> **Stub.** This skill is a placeholder. Content will be authored in a future workstream.

plugins/core/skills/zoom-out/SKILL.md

@@ -0,0 +1,10 @@
+---
+name: zoom-out
+description: >
+  Use when you want to step back from implementation details and review
+  the broader design, direction, or architectural coherence. Stub — full content not yet written.
+metadata:
+  category: cross-cutting
+---
+
+> **Stub.** This skill is a placeholder. Content will be authored in a future workstream.