Add version field to 27 local-sourced plugins

Local-path plugins (source is a string like "./plugins/foo" in
marketplace.json) without a manifest version cache at
~/.claude/plugins/cache/{marketplace}/{plugin}/unknown/ forever.

The cache check in claude-cli's copyPluginToVersionedCache sees
pathExists(.../unknown/) → true → skips re-extraction, even after
the marketplace content updates. Users are stuck with stale plugin
files until they manually delete the cache.

Adding "version": "1.0.0" fixes this because calculatePluginVersion
reads the manifest from the freshly-synced marketplace tree (not the
stale cache), and manifest.version is priority #1 in version
resolution. New version → new cache path → cache miss → re-extract.

This is preferable to the GCS-SHA fallback approach
(anthropics/claude-cli-internal#24773) because:
- Per-plugin granularity: only bumped plugins re-extract, not all
  27 on every marketplace push
- No disk accumulation from unrelated marketplace churn
- Fixes both the runtime loader path AND the migration path
  (manifest.version is priority #1 in both)
- No claude-cli code change needed

Remote-sourced plugins (github/git/url) already get a git SHA as
their version and are unaffected.

plugins/mcp-server-dev/.claude-plugin/plugin.json

@@ -1,6 +1,7 @@
 {
   "name": "mcp-server-dev",
-  "description": "Skills for designing and building MCP servers that work seamlessly with Claude — guides you through deployment models (remote HTTP, MCPB, local), tool design patterns, auth, and interactive MCP apps.",
+  "version": "1.0.0",
+  "description": "Skills for designing and building MCP servers that work seamlessly with Claude \u2014 guides you through deployment models (remote HTTP, MCPB, local), tool design patterns, auth, and interactive MCP apps.",
   "author": {
     "name": "Anthropic",
     "email": "support@anthropic.com"