feat: package as a Claude Code plugin with a deterministic quality gate

Workflows move to skills/<name>/SKILL.md so the repo installs as a plugin.
scripts/quality-gate runs only the checks of the requested tier on the diff
and reports missing tools as unverified instead of passing them. Hooks block
stopping on a failed or stale gate, guard destructive shell commands and
format edited files with the project's own formatter.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

.claude-plugin/plugin.json

@@ -0,0 +1,14 @@
+{
+  "name": "dev-workflows",
+  "displayName": "Dev Workflows",
+  "version": "2.0.0",
+  "description": "Workflows de desenvolvimento que escalam com o tamanho do pedido: roteador por nível, agentes com permissão mínima, gate de qualidade determinístico e revisão de segurança com fontes ao vivo.",
+  "author": {
+    "name": "Evandro Fonseca Junior",
+    "url": "https://github.com/evandrodevbr"
+  },
+  "homepage": "https://github.com/evandrodevbr/dev-workflows",
+  "repository": "https://github.com/evandrodevbr/dev-workflows",
+  "license": "MIT",
+  "keywords": ["workflow", "code-review", "security", "frontend", "backend", "quality-gate"]
+}