feat: Phase 0+1 — repo sync, pino, lint fixes, core components

Phase 0:
- Synced latest live-status.js from workspace (9928 bytes)
- Fixed 43 lint issues: empty catch blocks, console statements
- Added pino dependency
- Created src/tool-labels.json with all known tool mappings
- make check passes

Phase 1 (Core Components):
- src/config.js: env-var config with validation, throws on missing required vars
- src/logger.js: pino singleton with child loggers, level validation
- src/circuit-breaker.js: CLOSED/OPEN/HALF_OPEN state machine with callbacks
- src/tool-labels.js: exact/prefix/regex tool->label resolver with external override
- src/status-box.js: Mattermost post manager (keepAlive, throttle, retry, circuit breaker)
- src/status-formatter.js: pure SessionState->text formatter (nested, compact)
- src/health.js: HTTP health endpoint + metrics
- src/status-watcher.js: JSONL file watcher (inotify, compaction detection, idle detection)

Tests:
- test/unit/config.test.js: 7 tests
- test/unit/circuit-breaker.test.js: 12 tests
- test/unit/logger.test.js: 5 tests
- test/unit/status-formatter.test.js: 20 tests
- test/unit/tool-labels.test.js: 15 tests

All 59 unit tests pass. make check clean.

src/health.js

@@ -0,0 +1,118 @@
+'use strict';
+
+/**
+ * health.js — HTTP health endpoint + metrics.
+ *
+ * GET /health -> JSON { status, activeSessions, uptime, lastError, metrics }
+ * GET /metrics -> JSON { detailed metrics }
+ */
+
+/* eslint-disable no-console */
+
+const http = require('http');
+
+class HealthServer {
+  /**
+   * @param {object} opts
+   * @param {number} opts.port - Port to listen on (0 = disabled)
+   * @param {Function} opts.getMetrics - Callback that returns metrics object
+   * @param {object} [opts.logger] - pino logger
+   */
+  constructor(opts) {
+    this.port = opts.port;
+    this.getMetrics = opts.getMetrics;
+    this.logger = opts.logger || null;
+    this.server = null;
+    this.startTime = Date.now();
+  }
+
+  start() {
+    if (this.port === 0) {
+      if (this.logger) this.logger.info('Health server disabled (port=0)');
+      return Promise.resolve();
+    }
+
+    return new Promise((resolve, reject) => {
+      this.server = http.createServer((req, res) => {
+        this._handleRequest(req, res);
+      });
+
+      this.server.on('error', (err) => {
+        if (this.logger) {
+          this.logger.error({ err }, 'Health server error');
+        } else {
+          console.error('Health server error:', err.message);
+        }
+        reject(err);
+      });
+
+      this.server.listen(this.port, '127.0.0.1', () => {
+        if (this.logger) {
+          this.logger.info({ port: this.port }, 'Health server listening');
+        }
+        resolve();
+      });
+    });
+  }
+
+  stop() {
+    return new Promise((resolve) => {
+      if (!this.server) {
+        resolve();
+        return;
+      }
+      this.server.close(() => resolve());
+    });
+  }
+
+  _handleRequest(req, res) {
+    const url = new URL(req.url, `http://localhost:${this.port}`);
+
+    if (req.method !== 'GET') {
+      res.writeHead(405, { 'Content-Type': 'application/json' });
+      res.end(JSON.stringify({ error: 'Method not allowed' }));
+      return;
+    }
+
+    let body;
+    switch (url.pathname) {
+      case '/health':
+        body = this._buildHealthResponse();
+        break;
+      case '/metrics':
+        body = this._buildMetricsResponse();
+        break;
+      default:
+        res.writeHead(404, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'Not found' }));
+        return;
+    }
+
+    res.writeHead(200, { 'Content-Type': 'application/json' });
+    res.end(JSON.stringify(body, null, 2));
+  }
+
+  _buildHealthResponse() {
+    const metrics = this.getMetrics();
+    const status = metrics.circuit && metrics.circuit.state === 'open' ? 'degraded' : 'healthy';
+
+    return {
+      status,
+      uptime: Math.floor((Date.now() - this.startTime) / 1000),
+      activeSessions: metrics.activeSessions || 0,
+      lastError: metrics.lastError || null,
+      metrics: {
+        updates_sent: metrics.updatesSent || 0,
+        updates_failed: metrics.updatesFailed || 0,
+        circuit_state: metrics.circuit ? metrics.circuit.state : 'unknown',
+        queue_depth: metrics.queueDepth || 0,
+      },
+    };
+  }
+
+  _buildMetricsResponse() {
+    return this.getMetrics();
+  }
+}
+
+module.exports = { HealthServer };