feat: SOTA Image to Base64 converter with 6 output formats (#65)

* feat(image-to-base64): register tool in shared constants and i18n

* feat(image-to-base64): add API route with Sharp pipeline and base64 encoding

* feat(image-to-base64): add Zustand store for base64 results

* feat(image-to-base64): add settings panel component

* feat(image-to-base64): add results panel with 6-tab output and batch accordion

* feat(image-to-base64): register tool in frontend tool registry

* fix(image-to-base64): pass through original buffer when no resize/conversion needed

---------

Co-authored-by: stirling-image <stirling-image@users.noreply.github.com>

apps/web/src/stores/base64-store.ts

@@ -0,0 +1,42 @@
+import { create } from "zustand";
+
+export interface Base64Result {
+  filename: string;
+  mimeType: string;
+  width: number;
+  height: number;
+  originalSize: number;
+  encodedSize: number;
+  overheadPercent: number;
+  base64: string;
+  dataUri: string;
+}
+
+export interface Base64Error {
+  filename: string;
+  error: string;
+}
+
+interface Base64State {
+  results: Base64Result[];
+  errors: Base64Error[];
+  processing: boolean;
+  expandedIndex: number;
+
+  setResults: (results: Base64Result[], errors: Base64Error[]) => void;
+  setProcessing: (v: boolean) => void;
+  setExpandedIndex: (i: number) => void;
+  reset: () => void;
+}
+
+export const useBase64Store = create<Base64State>((set) => ({
+  results: [],
+  errors: [],
+  processing: false,
+  expandedIndex: 0,
+
+  setResults: (results, errors) => set({ results, errors, expandedIndex: 0 }),
+  setProcessing: (v) => set({ processing: v }),
+  setExpandedIndex: (i) => set({ expandedIndex: i }),
+  reset: () => set({ results: [], errors: [], processing: false, expandedIndex: 0 }),
+}));