Update to v0.1.18 with per-collector intervals and tmux check

- Implement per-collector interval timing respecting NixOS config
- Remove all hardcoded timeout/interval values and make configurable
- Add tmux session requirement check for TUI mode (bypassed for headless)
- Update agent to send config hash in Build field instead of nixos version
- Add nginx check interval, HTTP timeouts, and ZMQ transmission interval configs
- Update NixOS configuration with new configurable values

Breaking changes:
- Build field now shows nix store config hash (8 chars) instead of nixos version
- All intervals now follow individual collector configuration instead of global

New configuration fields:
- systemd.nginx_check_interval_seconds
- systemd.http_timeout_seconds
- systemd.http_connect_timeout_seconds
- zmq.transmission_interval_seconds

Cargo.lock

@@ -270,7 +270,7 @@ checksum = "a1d728cc89cf3aee9ff92b05e62b19ee65a02b5702cff7d5a377e32c6ae29d8d"
 
 [[package]]
 name = "cm-dashboard"
-version = "0.1.16"
+version = "0.1.18"
 dependencies = [
  "anyhow",
  "chrono",
@@ -291,7 +291,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-agent"
-version = "0.1.16"
+version = "0.1.18"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -314,7 +314,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-shared"
-version = "0.1.16"
+version = "0.1.18"
 dependencies = [
  "chrono",
  "serde",