docs: improve CLI help, shell completion, and README

- Add command groups (Getting Started, Search, Downloads, Daemon, System)
- Add shell completion command (bash, zsh, fish, powershell)
- Add flag completions for --type, --quality, --sort, --lang, --genre,
  --country, --method, --player
- Improve Long descriptions and Examples for all commands
- Split doctor disk check into platform-specific files (Unix/Windows)
- Validate infoHash length before truncating (prevent panic)
- Fix references to non-existent 'unarr daemon start' command
- Move stats command to System & Diagnostics group
- Rewrite README with complete documentation, correct config format
  (toml not yaml), all commands, shell completion section

internal/cmd/reload_windows.go

@@ -0,0 +1,13 @@
+//go:build windows
+
+package cmd
+
+import "github.com/torrentclaw/torrentclaw-cli/internal/agent"
+
+// ReloadableConfig holds a reference to the daemon for hot-reload.
+type ReloadableConfig struct {
+	Daemon *agent.Daemon
+}
+
+// startReloadWatcher is a no-op on Windows (no SIGUSR1 support).
+func startReloadWatcher(_ *ReloadableConfig) {}