system: enforce absolute paths

This is less error-prone, and is quite easy to integrate considering internal/app has already migrated to container.Absolute.

Closes #11.

Signed-off-by: Ophestra <cat@gensokyo.uk>

system/link.go

@@ -3,15 +3,18 @@ package system
 import (
 	"fmt"
 
+	"hakurei.app/container"
 	"hakurei.app/hst"
 )
 
 // Link calls LinkFileType with the [Process] criteria.
-func (sys *I) Link(oldname, newname string) *I { return sys.LinkFileType(Process, oldname, newname) }
+func (sys *I) Link(oldname, newname *container.Absolute) *I {
+	return sys.LinkFileType(Process, oldname, newname)
+}
 
 // LinkFileType maintains a hardlink until its [Enablement] is no longer satisfied.
-func (sys *I) LinkFileType(et hst.Enablement, oldname, newname string) *I {
-	sys.ops = append(sys.ops, &hardlinkOp{et, newname, oldname})
+func (sys *I) LinkFileType(et hst.Enablement, oldname, newname *container.Absolute) *I {
+	sys.ops = append(sys.ops, &hardlinkOp{et, newname.String(), oldname.String()})
 	return sys
 }