feat(api): http eTag caching for all API calls

this will reduce the network load

komga/src/main/kotlin/org/gotson/komga/infrastructure/security/SecurityConfiguration.kt

@@ -55,9 +55,11 @@ class SecurityConfiguration(
 
       // authorize frames for H2 console
       .and()
-      .headers().frameOptions().sameOrigin()
+      .headers {
+        it.frameOptions().sameOrigin()
+        it.cacheControl().disable() //headers are set in WebMvcConfiguration
+      }
 
-      .and()
       .httpBasic()
 
       .and()

komga/src/main/kotlin/org/gotson/komga/infrastructure/web/Utils.kt

@@ -13,7 +13,10 @@ fun filePathToUrl(filePath: String): URL =
   Paths.get(filePath).toUri().toURL()
 
 fun ResponseEntity.BodyBuilder.setCachePrivate() =
-  this.cacheControl(CacheControl.maxAge(0, TimeUnit.SECONDS)
-    .cachePrivate()
-    .mustRevalidate()
-  )
+  this.cacheControl(cachePrivate)
+
+val cachePrivate = CacheControl
+  .maxAge(0, TimeUnit.SECONDS)
+  .noTransform()
+  .cachePrivate()
+  .mustRevalidate()

komga/src/main/kotlin/org/gotson/komga/infrastructure/web/WebMvcConfiguration.kt

@@ -6,13 +6,15 @@ import org.springframework.stereotype.Component
 import org.springframework.web.bind.annotation.ControllerAdvice
 import org.springframework.web.bind.annotation.ExceptionHandler
 import org.springframework.web.servlet.NoHandlerFoundException
+import org.springframework.web.servlet.config.annotation.InterceptorRegistry
 import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer
+import org.springframework.web.servlet.mvc.WebContentInterceptor
 import java.util.concurrent.TimeUnit
 
 
 @Configuration
-class StaticResourceConfiguration : WebMvcConfigurer {
+class WebMvcConfiguration : WebMvcConfigurer {
   override fun addResourceHandlers(registry: ResourceHandlerRegistry) {
     if (!registry.hasMappingForPattern("/webjars/**")) {
       registry.addResourceHandler("/webjars/**")
@@ -51,6 +53,17 @@ class StaticResourceConfiguration : WebMvcConfigurer {
       )
       .setCacheControl(CacheControl.maxAge(365, TimeUnit.DAYS).cachePublic())
   }
+
+  override fun addInterceptors(registry: InterceptorRegistry) {
+    registry.addInterceptor(
+      WebContentInterceptor().apply {
+        addCacheMapping(
+          cachePrivate,
+          "/api/**", "/opds/**"
+        )
+      }
+    )
+  }
 }
 
 @Component

komga/src/main/kotlin/org/gotson/komga/interfaces/rest/BookController.kt

@@ -191,16 +191,12 @@ class BookController(
   fun getBookThumbnail(
     @AuthenticationPrincipal principal: KomgaPrincipal,
     @PathVariable bookId: String
-  ): ResponseEntity<ByteArray> {
+  ): ByteArray {
     bookRepository.getLibraryId(bookId)?.let {
       if (!principal.user.canAccessLibrary(it)) throw ResponseStatusException(HttpStatus.FORBIDDEN)
     } ?: throw ResponseStatusException(HttpStatus.NOT_FOUND)
 
-    return bookLifecycle.getThumbnailBytes(bookId)?.let {
-      ResponseEntity.ok()
-        .setCachePrivate()
-        .body(it)
-    } ?: throw ResponseStatusException(HttpStatus.NOT_FOUND)
+    return bookLifecycle.getThumbnailBytes(bookId) ?: throw ResponseStatusException(HttpStatus.NOT_FOUND)
   }
 
   @Operation(description = "Download the book file.")

komga/src/main/kotlin/org/gotson/komga/interfaces/rest/SeriesController.kt

@@ -23,7 +23,6 @@ import org.gotson.komga.infrastructure.jooq.UnpagedSorted
 import org.gotson.komga.infrastructure.security.KomgaPrincipal
 import org.gotson.komga.infrastructure.swagger.PageableAsQueryParam
 import org.gotson.komga.infrastructure.swagger.PageableWithoutSortAsQueryParam
-import org.gotson.komga.infrastructure.web.setCachePrivate
 import org.gotson.komga.interfaces.rest.dto.BookDto
 import org.gotson.komga.interfaces.rest.dto.CollectionDto
 import org.gotson.komga.interfaces.rest.dto.SeriesDto
@@ -38,7 +37,6 @@ import org.springframework.data.domain.Pageable
 import org.springframework.data.domain.Sort
 import org.springframework.http.HttpStatus
 import org.springframework.http.MediaType
-import org.springframework.http.ResponseEntity
 import org.springframework.security.access.prepost.PreAuthorize
 import org.springframework.security.core.annotation.AuthenticationPrincipal
 import org.springframework.web.bind.annotation.DeleteMapping
@@ -196,16 +194,12 @@ class SeriesController(
   fun getSeriesThumbnail(
     @AuthenticationPrincipal principal: KomgaPrincipal,
     @PathVariable(name = "seriesId") seriesId: String
-  ): ResponseEntity<ByteArray> {
+  ): ByteArray {
     seriesRepository.getLibraryId(seriesId)?.let {
       if (!principal.user.canAccessLibrary(it)) throw ResponseStatusException(HttpStatus.FORBIDDEN)
     } ?: throw ResponseStatusException(HttpStatus.NOT_FOUND)
 
-    return seriesLifecycle.getThumbnailBytes(seriesId)?.let {
-      ResponseEntity.ok()
-        .setCachePrivate()
-        .body(it)
-    } ?: throw ResponseStatusException(HttpStatus.NOT_FOUND)
+    return seriesLifecycle.getThumbnailBytes(seriesId) ?: throw ResponseStatusException(HttpStatus.NOT_FOUND)
   }
 
   @PageableAsQueryParam