feat(cc-config): add and remove MCP servers through the claude CLI

Mutation goes through `claude mcp add|remove`, never a direct edit of
~/.claude.json — the running CLI rewrites that file concurrently, so a
dashboard write would race it. Reads stay on readMcpServers.

The plan specified a --url flag; the real CLI (v2.1.266) has none —
commandOrUrl is positional, and --header must trail it or the variadic
flag swallows the url. Built against the verified shape.

client/src/i18n/locales/en/ccConfig.json

@@ -129,6 +129,8 @@
   "mcp": {
     "userScope": "User-scoped servers",
     "projectScope": "Project-scoped servers",
+    "name": "Name",
+    "scope": "Scope",
     "command": "Command",
     "args": "Args",
     "env": "Env names",
@@ -317,6 +319,16 @@
     "marketplaceAdded": "Added marketplace {{name}}.",
     "marketplaceUpdated": "Updated marketplace {{name}}.",
     "marketplaceRemoved": "Removed marketplace {{name}}.",
+    "addMcpTitle": "Add an MCP server",
+    "addMcpNamePlaceholder": "name",
+    "addMcpTransportStdio": "Command (stdio)",
+    "addMcpTransportHttp": "URL (http)",
+    "addMcpCommandPlaceholder": "npx -y @modelcontextprotocol/server-github",
+    "addMcpUrlPlaceholder": "https://mcp.example.com",
+    "addMcpButton": "Add",
+    "addMcpHelp": "Runs `claude mcp add`. Scope user/project only — a `local`-scoped server is the CLI's per-checkout layer and isn't offered here.",
+    "mcpAdded": "Added MCP server {{name}}.",
+    "mcpRemoved": "Removed MCP server {{name}}.",
     "hookEvent": "Event name (e.g. PreToolUse)",
     "hookAddEvent": "Add event",
     "hookRemoveEvent": "Remove event",