feat: migrate default config and templates to npm specifiers

- quartz.config.default.yaml: all 44 plugins use @quartz-community/* npm specifiers
- cli/templates/*.yaml: all 4 templates updated (default, blog, obsidian, ttrpg)
- bootstrap-cli.mjs: updated help text
- package.json: devDeps use npm semver ranges instead of github: specifiers
- gitLoader.ts: regeneratePluginIndex scans npm packages from node_modules
- install-plugins.ts: generates plugin index for npm packages
- Removed quartz.lock.json (only relevant for git-installed plugins)

package.json

@@ -73,8 +73,8 @@
     "yargs": "^18.0.0"
   },
   "devDependencies": {
-    "@quartz-community/types": "github:quartz-community/types",
-    "@quartz-community/utils": "github:quartz-community/utils",
+    "@quartz-community/types": "^0.2.1",
+    "@quartz-community/utils": "^0.1.0",
     "@types/hast": "^3.0.4",
     "@types/node": "^25.0.10",
     "@types/pretty-time": "^1.1.5",