feat: add format tools (SVG-to-raster, vectorize, GIF) and optimization (rename, favicon, image-to-PDF)

Add 6 tools for format conversion and optimization extras:
- svg-to-raster: SVG to PNG/JPG/WebP at custom resolution
- vectorize: raster to SVG via potrace (B&W and color modes)
- gif-tools: animated GIF resize, frame extraction, optimization
- bulk-rename: pattern-based file renaming with ZIP output
- favicon: generate all favicon/app icon sizes with manifest.json
- image-to-pdf: combine images into PDF using pdfkit

apps/api/src/routes/tools/vectorize.ts

@@ -0,0 +1,132 @@
+import { z } from "zod";
+import sharp from "sharp";
+import potrace from "potrace";
+import type { FastifyInstance } from "fastify";
+import { randomUUID } from "node:crypto";
+import { writeFile } from "node:fs/promises";
+import { join, basename } from "node:path";
+import { createWorkspace } from "../../lib/workspace.js";
+
+const settingsSchema = z.object({
+  colorMode: z.enum(["bw", "color"]).default("bw"),
+  threshold: z.number().min(0).max(255).default(128),
+  detail: z.enum(["low", "medium", "high"]).default("medium"),
+});
+
+function traceImage(
+  buffer: Buffer,
+  options: { threshold: number; turdSize: number; color?: string },
+): Promise<string> {
+  return new Promise((resolve, reject) => {
+    potrace.trace(buffer, options, (err: Error | null, svg: string) => {
+      if (err) reject(err);
+      else resolve(svg);
+    });
+  });
+}
+
+function posterize(
+  buffer: Buffer,
+  options: { steps: number; threshold: number },
+): Promise<string> {
+  return new Promise((resolve, reject) => {
+    potrace.posterize(buffer, options, (err: Error | null, svg: string) => {
+      if (err) reject(err);
+      else resolve(svg);
+    });
+  });
+}
+
+export function registerVectorize(app: FastifyInstance) {
+  app.post(
+    "/api/v1/tools/vectorize",
+    async (request, reply) => {
+      let fileBuffer: Buffer | null = null;
+      let filename = "output";
+      let settingsRaw: string | null = null;
+
+      try {
+        const parts = request.parts();
+        for await (const part of parts) {
+          if (part.type === "file") {
+            const chunks: Buffer[] = [];
+            for await (const chunk of part.file) {
+              chunks.push(chunk);
+            }
+            fileBuffer = Buffer.concat(chunks);
+            filename = basename(part.filename ?? "output").replace(/\.[^.]+$/, "");
+          } else if (part.fieldname === "settings") {
+            settingsRaw = part.value as string;
+          }
+        }
+      } catch (err) {
+        return reply.status(400).send({
+          error: "Failed to parse multipart request",
+          details: err instanceof Error ? err.message : String(err),
+        });
+      }
+
+      if (!fileBuffer || fileBuffer.length === 0) {
+        return reply.status(400).send({ error: "No image file provided" });
+      }
+
+      let settings: z.infer<typeof settingsSchema>;
+      try {
+        const parsed = settingsRaw ? JSON.parse(settingsRaw) : {};
+        const result = settingsSchema.safeParse(parsed);
+        if (!result.success) {
+          return reply.status(400).send({ error: "Invalid settings", details: result.error.issues });
+        }
+        settings = result.data;
+      } catch {
+        return reply.status(400).send({ error: "Settings must be valid JSON" });
+      }
+
+      try {
+        // Convert to BMP-compatible format for potrace (PNG)
+        const pngBuffer = await sharp(fileBuffer)
+          .grayscale()
+          .png()
+          .toBuffer();
+
+        const turdSize = settings.detail === "low" ? 10 : settings.detail === "high" ? 1 : 4;
+
+        let svg: string;
+
+        if (settings.colorMode === "color") {
+          // Color mode: posterize
+          svg = await posterize(pngBuffer, {
+            steps: settings.detail === "low" ? 3 : settings.detail === "high" ? 8 : 5,
+            threshold: settings.threshold,
+          });
+        } else {
+          // B&W mode: simple trace
+          svg = await traceImage(pngBuffer, {
+            threshold: settings.threshold,
+            turdSize,
+          });
+        }
+
+        const svgBuffer = Buffer.from(svg, "utf-8");
+        const outFilename = `${filename}.svg`;
+        const jobId = randomUUID();
+        const workspacePath = await createWorkspace(jobId);
+        const outputPath = join(workspacePath, "output", outFilename);
+        await writeFile(outputPath, svgBuffer);
+
+        return reply.send({
+          jobId,
+          downloadUrl: `/api/v1/download/${jobId}/${encodeURIComponent(outFilename)}`,
+          originalSize: fileBuffer.length,
+          processedSize: svgBuffer.length,
+          svgPreview: svg.length < 50000 ? svg : undefined,
+        });
+      } catch (err) {
+        return reply.status(422).send({
+          error: "Vectorization failed",
+          details: err instanceof Error ? err.message : "Unknown error",
+        });
+      }
+    },
+  );
+}