feat: add Claude Desktop extension (.mcpb) for single-user stdio mode

Adds a `mcpb/` directory containing a Claude Desktop Extension bundle
that lets users install nextcloud-mcp-server from Claude Desktop without
needing HTTPS — the extension uses stdio transport (already supported via
`nextcloud_mcp_server/stdio.py`) so no network connection or TLS is
required.

Bundle contents:
- `manifest.json` — extension metadata, user_config fields for
  NEXTCLOUD_HOST, NEXTCLOUD_USERNAME, and NEXTCLOUD_PASSWORD (sensitive,
  stored in OS keychain)
- `run.sh` — shell wrapper that locates `uvx` across common install
  paths (official uv installer at ~/.local/bin, Homebrew at
  /opt/homebrew/bin, etc.) since Claude Desktop uses a restricted PATH
- `.gitignore` — excludes the built *.mcpb artifact

Build the distributable with:
    npm install -g @anthropic-ai/mcpb
    cd mcpb && mcpb pack

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

mcpb/.gitignore

@@ -0,0 +1 @@
+*.mcpb

mcpb/manifest.json

@@ -0,0 +1,53 @@
+{
+  "manifest_version": "0.2",
+  "name": "nextcloud-mcp",
+  "version": "0.72.4",
+  "display_name": "Nextcloud MCP",
+  "description": "Access your Nextcloud instance (Notes, Calendar, Contacts, Files, Deck, Tables) from Claude Desktop.",
+  "long_description": "Connects Claude Desktop to your Nextcloud server via stdio transport. Supports Notes, Calendar (CalDAV), Contacts (CardDAV), Files (WebDAV), Deck, Tables, and Cookbook. Requires uv (https://docs.astral.sh/uv/) to be installed.",
+  "author": {
+    "name": "nextcloud-mcp-server contributors"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/cbcoutinho/nextcloud-mcp-server"
+  },
+  "homepage": "https://github.com/cbcoutinho/nextcloud-mcp-server",
+  "license": "AGPL-3.0",
+  "keywords": ["nextcloud", "notes", "calendar", "contacts", "files", "deck"],
+  "server": {
+    "type": "python",
+    "entry_point": ".",
+    "mcp_config": {
+      "command": "/bin/sh",
+      "args": ["${__dirname}/run.sh"],
+      "env": {
+        "NEXTCLOUD_HOST": "${user_config.nextcloud_host}",
+        "NEXTCLOUD_USERNAME": "${user_config.nextcloud_username}",
+        "NEXTCLOUD_PASSWORD": "${user_config.nextcloud_password}"
+      }
+    }
+  },
+  "tools_generated": true,
+  "user_config": {
+    "nextcloud_host": {
+      "type": "string",
+      "title": "Nextcloud URL",
+      "description": "Your Nextcloud instance URL, e.g. https://cloud.example.com",
+      "required": true
+    },
+    "nextcloud_username": {
+      "type": "string",
+      "title": "Username",
+      "description": "Your Nextcloud username",
+      "required": true
+    },
+    "nextcloud_password": {
+      "type": "string",
+      "title": "App Password",
+      "description": "A Nextcloud app password (Settings \u2192 Security \u2192 App passwords). Stored securely in the OS keychain.",
+      "sensitive": true,
+      "required": true
+    }
+  }
+}

mcpb/run.sh

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+#!/bin/sh
+# Locate uvx — tries the official uv installer location first, then Homebrew, then PATH
+for candidate in \
+    "$HOME/.local/bin/uvx" \
+    "/opt/homebrew/bin/uvx" \
+    "/usr/local/bin/uvx" \
+    "/home/linuxbrew/.linuxbrew/bin/uvx"; do
+    if [ -x "$candidate" ]; then
+        exec "$candidate" nextcloud-mcp-server run --transport stdio
+    fi
+done
+
+# Fall back to whatever is in PATH
+exec uvx nextcloud-mcp-server run --transport stdio