fix(plugin): read API token from CLAUDE_PLUGIN_OPTION env, not user_config placeholder

The SessionStart push-channel hook passed the key via
SCRIBE_TOKEN="${user_config.api_token}" in hooks.json, but api_token is
sensitive:true. Claude Code keeps sensitive userConfig in the keychain and
does not interpolate it into hook command strings (only into mcpServers
headers), so the hook received the literal placeholder, sent it as the Bearer
token, and the context endpoint 401'd -> fail-open -> no context injected.

Read the harness-exported CLAUDE_PLUGIN_OPTION_<key> env vars instead (SCRIBE_*
still override for the settings.json dogfooding path), and treat any unexpanded
${...} literal as unset so the hook fails open cleanly instead of 401-ing.
Bump 0.1.1 -> 0.1.2 so installs refresh the cache.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugin/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "scribe",
   "description": "Scribe second brain for Claude Code: MCP tools over your notes/tasks/projects/rules, a session-start push channel that surfaces your always-on rules + active-project context, and a set of universal process-skills (brainstorm, debug, TDD, plan, verify). Replaces superpowers + file-memory with one app-backed plugin.",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "author": { "name": "Bryan Van Deusen" },
   "mcpServers": {
     "scribe": {