Initial t3bootstrap-skills plugin: three skills for T3Bootstrap on TYPO3 v14

- t3bootstrap-site-package: composer + site sets + when to add a local extension
- t3bootstrap-overrides: 4-layer override surface (Settings → SCSS → Fluid → DataProcessor)
- t3bootstrap-content-elements: 23 t3bs_* CE catalog + migration matrix (HTML/WP/Joomla/older TYPO3) + Flux-bs5 upgrade wizard

Mirrors the structure of wapplersystems/typo3-skills (.claude-plugin/{plugin.json,marketplace.json}, .agents/skills/<name>/{SKILL.md,agents/openai.yaml}).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "https://json.schemastore.org/claude-code-marketplace.json",
+  "name": "wapplersystems-t3bootstrap",
+  "description": "T3Bootstrap-spezifische Agent Skills für Claude Code (Schwester-Marketplace zu wapplersystems/typo3-skills)",
+  "owner": {
+    "name": "WapplerSystems",
+    "email": "info@wappler.systems"
+  },
+  "plugins": [
+    {
+      "name": "t3bootstrap-skills",
+      "source": "./",
+      "description": "Skills für Setup, Override und Content-Migration auf dem T3Bootstrap-Stack (TYPO3 v14)",
+      "category": "typo3",
+      "tags": ["typo3", "t3bootstrap", "bootstrap5", "fluid", "ddev"]
+    }
+  ]
+}

.claude-plugin/plugin.json

@@ -0,0 +1,25 @@
+{
+  "$schema": "https://json.schemastore.org/claude-code-plugin-manifest.json",
+  "name": "t3bootstrap-skills",
+  "version": "0.1.0",
+  "description": "Agent Skills für das T3Bootstrap-Ökosystem (TYPO3 v14): Site-Package-Setup auf den t3bootstrap/*- und wapplersystems/*-Extensions, minimal-invasive Template- und CSS-Overrides, Content-Element-Auswahl und Inhalts-Migration auf die b13/container-basierten t3bs_*-CEs (inkl. Flux-bs5 → Container-bs5 Migration). Ergänzt das typo3-skills-Plugin um T3Bootstrap-spezifische Workflows.",
+  "author": {
+    "name": "WapplerSystems",
+    "url": "https://wappler.systems"
+  },
+  "homepage": "https://git.wappler.systems/WapplerSystems/t3bootstrap-skills",
+  "repository": "https://git.wappler.systems/WapplerSystems/t3bootstrap-skills",
+  "license": "MIT",
+  "keywords": [
+    "typo3",
+    "typo3-v14",
+    "t3bootstrap",
+    "bootstrap5",
+    "site-package",
+    "content-elements",
+    "container",
+    "fluid",
+    "ddev"
+  ],
+  "skills": "./.agents/skills/"
+}