feat(sync): embed basic-auth credentials in restic URL

src/main/kotlin/center/timemachine/cloud/Sync.kt

@@ -29,10 +29,24 @@ fun readCredentials(tokenFile: Path): Pair<String, String> {
     return parts[0].trim() to parts[1].trim()
 }
 
-/** Build the restic --repo URL: rest:<base>/<discord_id>/ */
-private fun resticRepo(baseUrl: String, discordId: String): String {
-    val base = baseUrl.trimEnd('/').let { if (it.startsWith("rest:")) it else "rest:$it" }
-    return "$base/$discordId/"
+/**
+ * Build the restic --repo URL: rest:<scheme>://<discord_id>:<password>@<host>/<discord_id>/
+ *
+ * URL-embedded basic auth is universally supported by restic; the alternative
+ * (RESTIC_REST_USERNAME / RESTIC_REST_PASSWORD env vars) requires restic 0.16+.
+ * Same password is used for HTTP basic auth and restic repo encryption —
+ * cloud-svc provisions one password per user covering both.
+ */
+private fun resticRepo(baseUrl: String, discordId: String, password: String): String {
+    val raw = baseUrl.trimStart().removePrefix("rest:").trimEnd('/')
+    val schemeEnd = raw.indexOf("://")
+    require(schemeEnd > 0) { "--url must include a scheme (http:// or https://): $baseUrl" }
+    val scheme = raw.substring(0, schemeEnd + 3)
+    val hostAndPath = raw.substring(schemeEnd + 3)
+    // URL-encode credentials to handle special chars in the password
+    val u = java.net.URLEncoder.encode(discordId, Charsets.UTF_8)
+    val p = java.net.URLEncoder.encode(password, Charsets.UTF_8)
+    return "rest:$scheme$u:$p@$hostAndPath/$discordId/"
 }
 
 /** Common env applied to every restic invocation. */
@@ -52,7 +66,7 @@ private fun resticEnv(password: String): Map<String, String> = mapOf(
 fun pull(args: Args): Int {
     val (discordId, password) = readCredentials(args.tokenFile)
     val binary = Restic.resolveBinary(args)
-    val repo = resticRepo(args.url, discordId)
+    val repo = resticRepo(args.url, discordId, password)
     val env = resticEnv(password)
 
     // Check whether any snapshots exist
@@ -103,7 +117,7 @@ fun pull(args: Args): Int {
 fun push(args: Args): Int {
     val (discordId, password) = readCredentials(args.tokenFile)
     val binary = Restic.resolveBinary(args)
-    val repo = resticRepo(args.url, discordId)
+    val repo = resticRepo(args.url, discordId, password)
     val env = resticEnv(password)
 
     val scope = Scope_.load(args.packFolder)