Add README with usage example

Document the teesql T-SQL parser with installation instructions
and a complete code example showing parsing and JSON output.

Author: claude

README.md

@@ -0,0 +1,76 @@
+# teesql
+
+A T-SQL parser for Go that produces JSON AST output compatible with Microsoft's SqlScriptDOM.
+
+## Installation
+
+```bash
+go get github.com/kyleconroy/teesql
+```
+
+## Usage
+
+```go
+package main
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/kyleconroy/teesql/parser"
+)
+
+func main() {
+	sql := "SELECT id, name FROM users WHERE active = 1"
+
+	script, err := parser.Parse(context.Background(), strings.NewReader(sql))
+	if err != nil {
+		panic(err)
+	}
+
+	json, err := parser.MarshalScript(script)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(string(json))
+}
+```
+
+Output:
+
+```json
+{
+  "Batches": [
+    {
+      "Statements": [
+        {
+          "QueryExpression": {
+            "SelectElements": [
+              {"ColumnType": 2, "Identifier": {"Value": "id"}},
+              {"ColumnType": 2, "Identifier": {"Value": "name"}}
+            ],
+            "FromClause": {
+              "TableReferences": [
+                {"SchemaObject": {"BaseIdentifier": {"Value": "users"}}}
+              ]
+            },
+            "WhereClause": {
+              "SearchCondition": {
+                "FirstExpression": {"ColumnType": 2, "Identifier": {"Value": "active"}},
+                "ComparisonType": 0,
+                "SecondExpression": {"Value": "1"}
+              }
+            }
+          }
+        }
+      ]
+    }
+  ]
+}
+```
+
+## License
+
+MIT