fix: truncate filenames by bytes instead of characters to avoid File name too long (#1933)

* fix: truncate filenames by bytes instead of characters to avoid IOException File name too long

* add a CHANGELOG.md entry.

server/src/test/kotlin/suwayomi/tachidesk/SafePathTest.kt

@@ -0,0 +1,50 @@
+package suwayomi.tachidesk
+
+import xyz.nulldev.androidcompat.util.SafePath
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class SafePathTest {
+    @Test
+    fun invalidCharactersAreReplacedAndEdgesAreTrimmed() {
+        val input = " .a:b*c?d<e>f|g\\h/i. "
+
+        val result = SafePath.buildValidFilename(input)
+
+        assertEquals("a_b_c_d_e_f_g_h_i", result)
+    }
+
+    @Test
+    fun emptyAfterTrimReturnsInvalidMarker() {
+        assertEquals("(invalid)", SafePath.buildValidFilename(" ...   . "))
+    }
+
+    @Test
+    fun resultIsTruncatedTo240Characters() {
+        val input = "a".repeat(300)
+
+        val result = SafePath.buildValidFilename(input)
+
+        assertEquals(240, result.length)
+        assertEquals("a".repeat(240), result)
+    }
+
+    @Test
+    fun mixed256CharactersCanExceed255Utf8Bytes() {
+        val mixed256 =
+            buildString {
+                repeat(128) {
+                    append('a')
+                    append('你')
+                }
+            }
+
+        val result = SafePath.buildValidFilename(mixed256)
+
+        assertEquals(120, result.length)
+        assertEquals(mixed256.take(120), result)
+        assertEquals(240, result.toByteArray(Charsets.UTF_8).size)
+        assertTrue(result.toByteArray(Charsets.UTF_8).size == 240)
+    }
+}