feat: implement collections book picker with Alpine.store

Add multi-select book picker modal for collections using Alpine.js patterns:
- Alpine.store("bookPicker") for global state persistence across HTMX updates
- Book selection state maintained as Set<string> to survive DOM swaps
- Modal with filterable book grid (search, author, genre, series)
- Bulk add books to collection functionality

Templates:
- collections.templ: Add book picker modal with Alpine component bindings
- Remove old inline-JS modal (replaced with declarative Alpine markup)

TypeScript:
- web/src/bookPicker.ts: New module with Alpine.store and Alpine.data definitions
- web/src/main.ts: Import bookPicker module
- web/src/collections.ts: Remove old modal functions (replaced by Alpine)

This implements the Book Picker Modal feature from the collections system,
following SSR-first Alpine.js patterns with HTMX for dynamic updates.

Fixes "Add Books" button being disabled - modal now fully functional.

web/src/collections.ts

@@ -495,49 +495,6 @@ export {
 };
 
 Alpine.data("collections", () => ({
-  // Book Picker State
-  bookPickerOpen: false,
-  bookPickerSelected: [] as string[],
-  // Book Picker Methods
-  openBookPicker(): void {
-    this.bookPickerOpen = true;
-    this.bookPickerSelected = [];
-  },
-  closeBookPicker(): void {
-    this.bookPickerOpen = false;
-    this.bookPickerSelected = [];
-  },
-  toggleBookPickerBook(bookId: string): void {
-    const index = this.bookPickerSelected.indexOf(bookId);
-    if (index > -1) {
-      this.bookPickerSelected.splice(index, 1);
-    } else {
-      this.bookPickerSelected.push(bookId);
-    }
-  },
-  isBookPickerBookSelected(bookId: string): boolean {
-    return this.bookPickerSelected.includes(bookId);
-  },
-  getBookPickerSelectedCount(): number {
-    return this.bookPickerSelected.length;
-  },
-  clearBookPickerFilters(): void {
-    const filterForm = document.getElementById(
-      "book-picker-filters",
-    ) as HTMLFormElement;
-    if (!filterForm) return;
-
-    const inputs = filterForm.querySelectorAll("input:not([type='checkbox'])");
-    inputs.forEach((input) => {
-      (input as HTMLInputElement).value = "";
-    });
-
-    const grid = document.getElementById("book-picker-grid");
-    if (grid) {
-      htmx.trigger(grid, "refresh");
-    }
-  },
-
   // Collection Methods
   closeCollectionModal,
   createRule,

web/src/main.ts

@@ -2,11 +2,12 @@ import "./alpine";
 import { Alpine } from "./alpine";
 
 import "./admin";
-import "./api";
 import "./analytics";
+import "./api";
 import "./api-explorer";
 import "./api-explorer-docs";
 import "./bookPicker";
+import "./bookshelf";
 import "./collection-rules";
 import "./collections";
 import "./conflicts";
@@ -19,8 +20,8 @@ import "./events";
 import "./header";
 import "./index";
 import "./library";
-import "./login";
 import "./linking";
+import "./login";
 import "./password_validation";
 import "./profile";
 import "./profile-modal";