Add godoc documentation to exported types and methods

Add proper godoc comments to exported items in:
- internal/globals: Appname, Version, Commit variables; Globals type; New function
- internal/log: LogLevel type; level constants; Config type; Initialize, Fatal,
  Error, Warn, Notice, Info, Debug functions and variants; TTYHandler type and
  methods; Module variable; LogOptions type

internal/globals/globals.go

@@ -4,13 +4,16 @@ import (
 	"time"
 )
 
-// these get populated from main() and copied into the Globals object.
-var (
-	Appname string = "vaultik"
-	Version string = "dev"
-	Commit  string = "unknown"
-)
+// Appname is the application name, populated from main().
+var Appname string = "vaultik"
 
+// Version is the application version, populated from main().
+var Version string = "dev"
+
+// Commit is the git commit hash, populated from main().
+var Commit string = "unknown"
+
+// Globals contains application-wide configuration and metadata.
 type Globals struct {
 	Appname   string
 	Version   string
@@ -18,6 +21,7 @@ type Globals struct {
 	StartTime time.Time
 }
 
+// New creates and returns a new Globals instance initialized with the package-level variables.
 func New() (*Globals, error) {
 	return &Globals{
 		Appname: Appname,