feat: Phase 7 — CLI complet (start/serve/stop/status/config/logs)

- Gestion PID (write/read/remove + verification processus)
- cmd_start: lance watcher + dashboard avec Ctrl+C graceful shutdown
- cmd_serve: dashboard seul (Linux) avec --no-watcher
- cmd_stop: kill processus via SIGTERM/OpenProcess + nettoyage PID
- cmd_status: affiche PID, dashboard URL, config, polling
- cmd_config show/set/reset: gestion dotted keys (imago.url, watcher.*, etc.)
- cmd_logs: affiche derniers logs
- Fix Default derives: ImagoConfig, DedupConfig, UiConfig, LoggingConfig
- Ajout dependances: open, libc (Unix)
- Watcher::run(self) au lieu de &self pour Send
- tests: start → API /api/health OK → stop → status OK
- 0 errors, 0 warnings (cargo check + cargo build --release)

src/imago_client.rs

@@ -1,6 +1,6 @@
 //! Client HTTP pour l'API Imago
 
-use anyhow::{Context, Result};
+use anyhow::Result;
 use reqwest::{Client, multipart};
 use serde::Deserialize;