chore: install kepubify into Docker image at build time

- download correct arch binary from projectx-tools during image build
- use system binary at /usr/local/bin/kepubify when available, fall back to runtime download for local dev

Dockerfile

@@ -40,8 +40,19 @@ RUN mkdir -p /deploy/migrations && cp -r /app/server/src/db/migrations/. /deploy
 FROM ${NODE_IMAGE} AS runtime
 WORKDIR /app
 
+ARG TARGETARCH
 RUN apk upgrade --no-cache && \
-    apk add --no-cache poppler-utils su-exec && \
+    apk add --no-cache poppler-utils su-exec curl && \
+    case "$TARGETARCH" in \
+      amd64) KEPUBIFY_BIN="kepubify-linux-64bit" ;; \
+      arm64) KEPUBIFY_BIN="kepubify-linux-arm64" ;; \
+      arm)   KEPUBIFY_BIN="kepubify-linux-arm" ;; \
+      386)   KEPUBIFY_BIN="kepubify-linux-32bit" ;; \
+    esac && \
+    curl -fsSL "https://github.com/neonsolstice/projectx-tools/raw/main/kepubify/${KEPUBIFY_BIN}" \
+      -o /usr/local/bin/kepubify && \
+    chmod +x /usr/local/bin/kepubify && \
+    apk del curl && \
     rm -rf /usr/local/lib/node_modules/npm /usr/local/bin/npm /usr/local/bin/npx
 
 ENV NODE_ENV=production

server/src/modules/kobo/services/kepubify-binary.service.test.ts

@@ -48,8 +48,19 @@ describe('KepubifyBinaryService', () => {
     expect(() => (service as any).detectBinaryName()).toThrow('Unsupported platform');
   });
 
-  it('caches computed binary path after first resolution', async () => {
+  it('returns system binary path when kepubify is already installed', async () => {
     const service = new KepubifyBinaryService(config as never);
+    statMock.mockResolvedValue({} as never);
+
+    await expect(service.getBinaryPath()).resolves.toBe('/usr/local/bin/kepubify');
+    await expect(service.getBinaryPath()).resolves.toBe('/usr/local/bin/kepubify');
+
+    expect(statMock).toHaveBeenCalledTimes(1);
+  });
+
+  it('caches computed binary path after first resolution when system binary absent', async () => {
+    const service = new KepubifyBinaryService(config as never);
+    statMock.mockRejectedValue(new Error('missing'));
     const detectSpy = vi.spyOn(service as any, 'detectBinaryName').mockReturnValue('kepubify-linux-64bit');
     const ensureSpy = vi.spyOn(service as any, 'ensureBinary').mockResolvedValue(undefined);
 

server/src/modules/kobo/services/kepubify-binary.service.ts

@@ -4,7 +4,8 @@ import { join } from 'path';
 import { Injectable, Logger } from '@nestjs/common';
 import { ConfigService } from '@nestjs/config';
 
-const KEPUBIFY_BASE_URL = 'https://github.com/booklore-app/booklore-tools/raw/main/kepubify/';
+const KEPUBIFY_BASE_URL = 'https://github.com/neonsolstice/projectx-tools/raw/main/kepubify/';
+const SYSTEM_BINARY_PATH = '/usr/local/bin/kepubify';
 
 @Injectable()
 export class KepubifyBinaryService {
@@ -18,6 +19,12 @@ export class KepubifyBinaryService {
 
   async getBinaryPath(): Promise<string> {
     if (this.cachedBinaryPath) return this.cachedBinaryPath;
+
+    if (await this.exists(SYSTEM_BINARY_PATH)) {
+      this.cachedBinaryPath = SYSTEM_BINARY_PATH;
+      return SYSTEM_BINARY_PATH;
+    }
+
     const binaryName = this.detectBinaryName();
     const toolsDir = join(this.appDataPath, '.tools', 'kepubify');
     const binaryPath = join(toolsDir, binaryName);
@@ -26,6 +33,15 @@ export class KepubifyBinaryService {
     return binaryPath;
   }
 
+  private async exists(path: string): Promise<boolean> {
+    try {
+      await stat(path);
+      return true;
+    } catch {
+      return false;
+    }
+  }
+
   private detectBinaryName(): string {
     const platform = process.platform;
     const arch = process.arch;