feat(lint): add lint-runner agent

Report-only agent that composes vale-config/vale-run to run a lint
sweep over a scope and return normalized findings — no Edit tool, it
flags issues rather than fixing them. Also lands the plugin manifest
scaffold (plugin.json, .claude-plugin/plugin.json) that the earlier
vale-config/vale-run skill commits assumed but didn't carry, bumped
to 1.1.0 for the new agent.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FxG5T8EJDgkABXxuneuFfn

plugins/lint/.claude-plugin/plugin.json

@@ -0,0 +1,18 @@
+{
+  "author": {
+    "name": "Defame1297",
+    "url": "https://git.dev.rkdr.net/Defame1297/"
+  },
+  "description": "Skills and agents for configuring and running linters, starting with Vale.",
+  "displayName": "Lint",
+  "keywords": [
+    "lint",
+    "vale",
+    "style",
+    "prose",
+    "linter"
+  ],
+  "license": "MIT",
+  "name": "lint",
+  "version": "1.1.0"
+}