feat: rewrite SDK from camelCase/requests to snake_case/httpx/Pydantic v2

- Replace OnspringApiSdk package with onspring_api_sdk package
- Add sync (OnspringClient) and async (AsyncOnspringClient) clients
- Migrate from requests to httpx for HTTP transport
- Migrate from raw dataclasses to Pydantic v2 models with alias support
- Add shared response handler module (_responses.py) to reduce duplication
- Add typed exceptions (OnspringError, OnspringAuthenticationError, etc.)
- Preserve full API coverage for apps, fields, files, lists, records, and reports

src/onspring_api_sdk/enums.py

@@ -0,0 +1,54 @@
+"""Enumerations for Onspring API data types and timespan configuration."""
+
+from enum import Enum
+
+
+class DataFormat(Enum):
+    """The possible data format types for record field values."""
+
+    Raw: int = 0
+    Formatted: int = 1
+
+
+class ReportDataType(Enum):
+    """The possible report data types for reports."""
+
+    ReportData: int = 0
+    ChartData: int = 1
+
+
+class ResultValueType(Enum):
+    """The possible types for record field values."""
+
+    String: int = 0
+    Integer: int = 1
+    Decimal: int = 2
+    Date: int = 3
+    TimeSpan: int = 4
+    Guid: int = 5
+    StringList: int = 6
+    IntegerList: int = 7
+    GuidList: int = 8
+    AttachmentList: int = 9
+    ScoringGroupList: int = 10
+    FileList: int = 11
+
+
+class Increment(Enum):
+    """Possible increment values for timespan data in an Onspring timespan field."""
+
+    Seconds: str = "Second(s)"
+    Minutes: str = "Minute(s)"
+    Hours: str = "Hour(s)"
+    Days: str = "Day(s)"
+    Weeks: str = "Week(s)"
+    Months: str = "Month(s)"
+    Years: str = "Year(s)"
+
+
+class Recurrence(Enum):
+    """Possible recurrence values for timespan data in an Onspring timespan field."""
+
+    Empty: str = "None"
+    EndByDate: str = "EndByDate"
+    EndAfterOccurrences: str = "EndAfterOccurrences"