Add Google Calendar integration and Claude docs

- New server/google_calendar.mjs wrapping googleapis v3 with auto token refresh
- Four new actions: calendar-list-events (auto-accept), calendar-create/update/delete-event (queue)
- bin/ccc-gcal-auth.mjs one-time OAuth2 consent flow helper
- config.example.json updated with google_calendar block
- server/config.mjs, index.mjs wired up following the same pattern as SMTP/mailer
- Bump version to 1.2.0
- Add CLAUDE.md and claude-info/ with architecture reference, feature plans, and contributing checklist

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

bin/ccc-gcal-auth.mjs

@@ -0,0 +1,86 @@
+#!/usr/bin/env node
+// One-time OAuth2 authorization flow for Google Calendar.
+// Run this on the host to generate a token file for the server.
+//
+// Usage:
+//   ccc-gcal-auth --credentials google-credentials.json --token google-token.json
+
+import { readFileSync, writeFileSync } from 'node:fs';
+import { createServer } from 'node:http';
+import { google } from 'googleapis';
+
+const SCOPES = ['https://www.googleapis.com/auth/calendar'];
+const PORT = 3016;
+const REDIRECT_URI = `http://localhost:${PORT}/callback`;
+
+function get_arg(argv, flag) {
+	const i = argv.indexOf(flag);
+	return i !== -1 ? argv[i + 1] : null;
+}
+
+const credentials_path = get_arg(process.argv, '--credentials');
+const token_path       = get_arg(process.argv, '--token');
+
+if (!credentials_path || !token_path) {
+	console.error('Usage: ccc-gcal-auth --credentials <path> --token <output-path>');
+	process.exit(1);
+}
+
+let credentials;
+try {
+	credentials = JSON.parse(readFileSync(credentials_path, 'utf8'));
+} catch (err) {
+	console.error(`Cannot read credentials file: ${err.message}`);
+	process.exit(1);
+}
+
+const { client_id, client_secret } = credentials.installed ?? credentials.web;
+const oauth2_client = new google.auth.OAuth2(client_id, client_secret, REDIRECT_URI);
+
+const auth_url = oauth2_client.generateAuthUrl({
+	access_type: 'offline',
+	scope: SCOPES,
+	prompt: 'consent',
+});
+
+console.log('Open this URL in your browser to authorize Google Calendar access:\n');
+console.log(auth_url);
+console.log(`\nListening for redirect on http://localhost:${PORT}/callback ...`);
+
+const server = createServer(async (req, res) => {
+	let url;
+	try {
+		url = new URL(req.url, `http://localhost:${PORT}`);
+	} catch (_) {
+		res.end('Bad request');
+		return;
+	}
+
+	if (url.pathname !== '/callback') {
+		res.end('Not found');
+		return;
+	}
+
+	const code = url.searchParams.get('code');
+	if (!code) {
+		res.writeHead(400);
+		res.end('Missing code parameter');
+		return;
+	}
+
+	try {
+		const { tokens } = await oauth2_client.getToken(code);
+		writeFileSync(token_path, JSON.stringify(tokens, null, '\t') + '\n', 'utf8');
+		res.end('Authorization successful. You may close this tab.');
+		console.log(`\nToken written to ${token_path}`);
+		server.close();
+	} catch (err) {
+		res.writeHead(500);
+		res.end(`Error: ${err.message}`);
+		console.error(`Token exchange failed: ${err.message}`);
+		server.close();
+		process.exit(1);
+	}
+});
+
+server.listen(PORT, '127.0.0.1');