Remove insecure NODE_TLS_REJECT_UNAUTHORIZED=0 TLS workaround

The MeshMonitor gateway uses a valid Let's Encrypt certificate, so
standard TLS certificate verification already works — no workaround
needed. The flag was a security downgrade: it disabled cert verification
for ALL outbound connections in the container (including the LLM and
opencode services), not just the gateway.

- docker-compose.yml: drop NODE_TLS_REJECT_UNAUTHORIZED env line + comment
- src/main.ts: drop process.env.NODE_TLS_REJECT_UNAUTHORIZED + comments
- CHANGELOG.md: correct the v0.22.0 Docker bullet wording

Part of the already-open MeshMonitor connection work (PR #56): no version
bump, no new changelog section.

Co-Authored-By: OpenCode <noreply@opencode.ai>

docker-compose.yml

@@ -7,8 +7,6 @@ services:
       MESHMONITOR_API_BASE: ${MESHMONITOR_API_BASE:-https://meshmonitor.kkhost.pl/api/v1}
       MESHMONITOR_SOURCE: ${MESHMONITOR_SOURCE:-default}
       MESHMONITOR_TIMEOUT_MS: ${MESHMONITOR_TIMEOUT_MS:-15000}
-      # the gateway uses a self-signed certificate
-      NODE_TLS_REJECT_UNAUTHORIZED: '0'
       MESH_DB_PATH: ./data/mesh-bot.db
       MESH_POLL_MS: '1000'
       MESH_NOTIFY_CHANNEL: '${MESH_NOTIFY_CHANNEL:-3}'