feat: storage path layout, basename URLs, and bidirectional domain isolation

Add storage_use_date_path for flat vs date-key storage layout and emit
basename-only public URLs when hide-folder is enabled. Block image paths
on the site host when domain separation is active so only the image host
serves files. Update settings UI, i18n, tests, and deployment docs.

server/utils/image-index.ts

@@ -2,8 +2,8 @@ import { promises as fs } from 'node:fs'
 import { join } from 'node:path'
 import { getDb } from './db'
 import { getDataDir } from './data-dir'
-import { DEFAULT_FOLDER, isValidFolderName, validateImageKey } from './image-key'
-import { isHiddenImageDatePath } from './image-public-path'
+import { DEFAULT_FOLDER, isValidFolderName, sortFolderNames, validateImageKey } from './image-key'
+import { isBareImageFilename, isHiddenImageDatePath } from './image-public-path'
 import {
   ensureDefaultBackends,
   ensureStorageSchema,
@@ -138,6 +138,29 @@ export function findImageKeyByDatePath(datePath: string): string | null {
   return defaultFolder?.key ?? rows[0]!.key
 }
 
+/** 隐藏目录 URL（纯文件名）反查完整 key；多目录同名时优先 images */
+export function findImageKeyByFilename(filename: string): string | null {
+  if (!isBareImageFilename(filename)) return null
+
+  ensureStorageSchema()
+  const suffix = `/${filename}`
+  const rows = getDb().prepare(`
+    SELECT key FROM images WHERE key LIKE ?
+  `).all(`%${suffix}`) as Array<{ key: string }>
+
+  if (rows.length === 0) {
+    const flatFallback = `${DEFAULT_FOLDER}/${filename}`
+    return validateImageKey(flatFallback) ? flatFallback : null
+  }
+  if (rows.length === 1) return rows[0]!.key
+
+  const exactDefault = rows.find(row => row.key === `${DEFAULT_FOLDER}/${filename}`)
+  if (exactDefault) return exactDefault.key
+
+  const defaultFolder = rows.find(row => row.key.startsWith(`${DEFAULT_FOLDER}/`))
+  return defaultFolder?.key ?? rows[0]!.key
+}
+
 async function readDirNames(path: string): Promise<string[]> {
   try {
     const entries = await fs.readdir(path, { withFileTypes: true })
@@ -164,8 +187,16 @@ async function listLocalImageKeys(): Promise<string[]> {
   for (const prefix of prefixes) {
     if (!isValidFolderName(prefix)) continue
     const root = join(dataDir, prefix)
+    const rootFiles = await readFileNames(root)
+    for (const file of rootFiles) {
+      if (file.endsWith(META_SUFFIX)) continue
+      const key = `${prefix}/${file}`
+      if (validateImageKey(key)) keys.push(key)
+    }
+
     const years = await readDirNames(root)
     for (const year of years) {
+      if (!/^\d{4}$/.test(year)) continue
       const months = await readDirNames(join(root, year))
       for (const month of months) {
         const files = await readFileNames(join(root, year, month))
@@ -222,10 +253,7 @@ export async function listFolders(): Promise<string[]> {
   `).all() as Array<{ folder: string }>
 
   const folders = rows.map(row => row.folder).filter(isValidFolderName)
-  if (!folders.includes(DEFAULT_FOLDER)) {
-    folders.push(DEFAULT_FOLDER)
-  }
-  return folders.sort((a, b) => a.localeCompare(b))
+  return sortFolderNames(folders)
 }
 
 export async function listFoldersForUser(
@@ -240,10 +268,7 @@ export async function listFoldersForUser(
   `).all(...params) as Array<{ folder: string }>
 
   const folders = rows.map(row => row.folder).filter(isValidFolderName)
-  if (!folders.length) {
-    folders.push(DEFAULT_FOLDER)
-  }
-  return folders.sort((a, b) => a.localeCompare(b))
+  return sortFolderNames(folders)
 }
 
 function buildBackendFilterSql(