Set up Go module and project structure

- Populated .gitignore with Go-specific patterns
- Created placeholder Go files with basic package structure:
  - bookstack.go: Client and Config setup
  - types.go: Data structures (Book, Page, Chapter, Shelf, SearchResult)
  - errors.go: Error handling types with sentinel errors
  - http.go: HTTP helper placeholder with ListOptions
  - books.go, pages.go, chapters.go, shelves.go, search.go: Service placeholders
- Verified build succeeds with go build ./...
- No external dependencies added (stdlib only)

All files compile successfully and follow flat package structure.

http.go

@@ -0,0 +1,28 @@
+package bookstack
+
+import (
+	"context"
+	"net/http"
+)
+
+// buildRequest creates an HTTP request with proper authentication headers.
+// TODO: Implement request building with Authorization header (Token <id>:<secret>)
+func (c *Client) buildRequest(ctx context.Context, method, path string, body interface{}) (*http.Request, error) {
+	// Placeholder for future implementation
+	return nil, nil
+}
+
+// doRequest executes an HTTP request and handles the response.
+// TODO: Implement response handling, error parsing, and JSON unmarshaling
+func (c *Client) doRequest(ctx context.Context, req *http.Request, v interface{}) error {
+	// Placeholder for future implementation
+	return nil
+}
+
+// ListOptions contains common options for list operations.
+type ListOptions struct {
+	Count  int               // Max items per page (default 100, max 500)
+	Offset int               // Offset for pagination
+	Sort   string            // Sort field (e.g., "name", "-created_at")
+	Filter map[string]string // Filters (e.g., {"name": "value"})
+}