fix: resolve 14 security, correctness, and robustness issues found during QA sweep

Security fixes:
- Add auth + ownership check to thumbnail endpoint (was unauthenticated)
- Validate ExifTool fieldsToRemove against safe tag name pattern
- Add SVG sanitization to pipeline execute and batch endpoints
- Replace basename() with sanitizeFilename() in 16 tool routes
- Escape SQL LIKE wildcards in file search to prevent pattern injection
- Improve settings HTML tag validation pattern

Bug fixes:
- Skip autoOrient for SVG inputs in pipeline (prevents misinterpretation)
- Remove double-encode in compress targetSize (was degrading quality)
- Fix bg-effects alpha value from 255 to 1.0 (Sharp expects float)
- Guard download stream error handler against headers-already-sent race
- Use O_EXCL atomic file creation for install lock (fixes TOCTOU race)
- Truncate collage file array to template image count

UX fixes:
- Accept empty JSON bodies on POST endpoints (install/uninstall)
- Custom JSON content type parser that treats empty body as {}

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

@@ -1,5 +1,4 @@
 import { randomUUID } from "node:crypto";
-import { basename, extname } from "node:path";
 import archiver from "archiver";
 import type { FastifyInstance } from "fastify";
 import sharp from "sharp";
@@ -7,6 +6,7 @@ import { z } from "zod";
 import { autoOrient } from "../../lib/auto-orient.js";
 import { formatZodErrors } from "../../lib/errors.js";
 import { validateImageBuffer } from "../../lib/file-validation.js";
+import { sanitizeFilename } from "../../lib/filename.js";
 import { ensureSharpCompat } from "../../lib/heic-converter.js";
 
 const settingsSchema = z.object({}).passthrough();
@@ -39,7 +39,7 @@ export function registerFavicon(app: FastifyInstance) {
             chunks.push(chunk);
           }
           const buffer = Buffer.concat(chunks);
-          const filename = basename(part.filename ?? `image-${uploadedFiles.length + 1}`);
+          const filename = sanitizeFilename(part.filename ?? `image-${uploadedFiles.length + 1}`);
           uploadedFiles.push({ buffer, filename });
         } else if (part.fieldname === "settings") {
           settingsRaw = part.value as string;
@@ -97,7 +97,7 @@ export function registerFavicon(app: FastifyInstance) {
       for (const file of uploadedFiles) {
         // Decode HEIC/HEIF if needed, then normalize EXIF orientation
         const decoded = await autoOrient(await ensureSharpCompat(file.buffer));
-        const stem = basename(file.filename, extname(file.filename));
+        const stem = sanitizeFilename(file.filename).replace(/\.[^.]+$/, "");
         // Single file: flat structure. Multiple files: per-image folders.
         const prefix = isSingleFile ? "" : `${stem}/`;