Refactor placeholder constants into dedicated file

Moved REPO_NAME and related constants into Placeholders.kt to improve code organization and maintainability. The code now dynamically references these constants where needed, simplifying updates and ensuring consistency across modules. Updated relevant imports and references to accommodate these changes.

src/jvmMain/kotlin/nl/astraeus/tmpl/Main.kt

@@ -13,8 +13,6 @@ import nl.astraeus.tmpl.web.RequestHandler
 
 val log = Logger()
 
-val REPO_NAME = "dummy so the gitea template compiles, please remove"
-
 val SERVER_PORT = 7001
 val JDBC_PORT = 8001
 
@@ -37,7 +35,7 @@ fun main() {
   Class.forName("nl.astraeus.jdbc.Driver")
   Database.initialize(HikariConfig().apply {
     driverClassName = "nl.astraeus.jdbc.Driver"
-    jdbcUrl = "jdbc:stat:webServerPort=$JDBC_PORT:jdbc:sqlite:data/${REPO_NAME}.db"
+    jdbcUrl = "jdbc:stat:webServerPort=$JDBC_PORT:jdbc:sqlite:data/$repoName.db"
     username = "sa"
     password = ""
     maximumPoolSize = 25