refactor: improve installer code

- Refactor installer code for better readability and maintainability.
- Move `dagu_server.vsh` to `examples/virt/daguserver/dagu_server.vsh`.
- Remove unnecessary `println` statements.
- Improve error handling in `zinit_installer_actions.v`.
- Update `zinit_installer_actions.v` startup type to systemd.
- Refactor several factory functions.

examples/installers/dagu.vsh

@@ -1,15 +1,16 @@
 #!/usr/bin/env -S v -n -w -gc none  -cc tcc -d use_openssl -enable-globals run
 
 import freeflowuniverse.herolib.installers.sysadmintools.daguserver
-import freeflowuniverse.herolib.installers.infra.zinit
+import freeflowuniverse.herolib.installers.infra.zinit_installer
 
 // make sure zinit is there and running, will restart it if needed
-mut z := zinit.get()!
-z.destroy()!
-z.start()!
+// mut z := zinit_installer.get()!
+// z.destroy()!
+// z.install()!
+// z.start()!
 
-// mut ds := daguserver.get()!
+mut ds := daguserver.get()!
 // ds.destroy()!
-// ds.start()!
+ds.start()!
 
-// println(ds)
+println(ds)

examples/installers/dagu_server.vsh

@@ -1,58 +0,0 @@
-#!/usr/bin/env -S v -n -w -gc none  -cc tcc -d use_openssl -enable-globals run
-
-import freeflowuniverse.herolib.installers.sysadmintools.daguserver
-
-// will call the installer underneith
-
-mut dserver := daguserver.new()!
-dserver.install()!
-dserver.restart()!
-
-println('DAGU installed & running')
-
-mut dagucl := dserver.client()!
-
-// name                 string  // The name of the DAG, which is optional. The default name is the name of the file.
-// description          ?string // A brief description of the DAG.
-// tags                 ?string // Free tags that can be used to categorize DAGs, separated by commas.
-// env                  ?map[string]string // Environment variables that can be accessed by the DAG and its steps.
-// restart_wait_sec     ?int // The number of seconds to wait after the DAG process stops before restarting it.
-// hist_retention_days  ?int // The number of days to retain execution history (not for log files).
-// delay_sec            ?int // The interval time in seconds between steps.
-// max_active_runs      ?int // The maximum number of parallel running steps.
-// max_cleanup_time_sec ?int // The maximum time to wait after sending a TERM signal to running steps before killing them.
-
-mut mydag := dagucl.dag_new(
-	nameswhere: 'test11'
-)
-
-// nr                int     @[required]
-// name              string  // The name of the step.
-// description       string  // A brief description of the step.
-// dir               string  // The working directory for the step.
-// command           string  // The command and parameters to execute.
-// stdout            string  // The file to which the standard output is written.
-// output            ?string // The variable to which the result is written.
-// script            ?string // The script to execute.
-// signal_on_stop    ?string // The signal name (e.g., SIGINT) to be sent when the process is stopped.
-// continue_on_error bool
-// depends           string
-// retry_nr       	int   = 3
-// retry_interval 	int = 5
-
-mydag.step_add(
-	script:         'ls /tmp'
-	retry_interval: 1
-	retry_nr:       3
-)!
-
-mydag.step_add(
-	script:         'ls /root'
-	retry_interval: 1
-	retry_nr:       3
-)!
-
-dagresult := dagucl.dag_register(mydag, start: true)!
-println(dagresult)
-
-println('DAGU should have new steps')

examples/installers/zinit_installer.vsh

@@ -3,5 +3,6 @@
 import freeflowuniverse.herolib.installers.infra.zinit_installer
 
 mut installer := zinit_installer.get()!
-// installer.install()!
+installer.install()!
 installer.start()!
+// installer.destroy()!