feat: Add W&B Weave Tracing Integration

[parambharat]

Summary

This PR adds W&B Weave as a new tracing provider in Dify, resolving the feature request in #14463. The integration follows similar patterns to the existing tracers, allowing users to track LLM calls, workflows, and tool usage in W&B Weave.

Motivation and Context

Many Dify users leverage Weights & Biases for their ML workflow tracking and would benefit from native W&B Weave integration. This addition gives users more flexibility in choosing tracing providers that align with their existing MLOps stack.

Weave offers specialized capabilities for LLM applications:

• Detailed call tracing with input/output capture
• Support for complex application flows
• Rich visualization and analytics
• Integration with evaluation frameworks

Implementation Details

The implementation:

• Adds Weave as a new tracing provider option
• Creates a WeaveConfig model for storing API key, entity, project, and endpoint configuration
• Implements a client wrapper for W&B Weave client
• Develops a tracer class implementing the BaseTraceInstance interface
• Integrates with Dify's existing trace queue management system

Dependencies

• Added dependency: weave package for Python SDK integration

The implementation follows Dify's existing patterns to ensure consistency while providing the new functionality needed for W&B Weave integration.

Resolves #14463

Checklist

• This change requires a documentation update, included: Dify Document :Docs PR

• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)

• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.

• I've updated the documentation accordingly.

• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[aiswaryasankarwork]

When inputs is a list of dictionaries, the usage_metadata and file_list are not added to each message in the list, potentially losing token usage tracking.

📝 Committable Code Suggestion

‼️ Ensure you review the code suggestion before committing it to the branch. Make sure it replaces the highlighted code, contains no missing lines, and has no issues with indentation.

Suggested change

	if field_name == "inputs":
	data = {
	"messages": v,
	}
	elif field_name == "outputs":
	if field_name == "inputs":
	data = {
	"messages": [dict(msg, **{"usage_metadata": usage_metadata, "file_list": file_list}) for msg in v] if isinstance(v, list) else v,
	}
	elif field_name == "outputs":

[aiswaryasankarwork]

Incorrect tuple creation in start_time and end_time attributes due to trailing comma, causing them to be tuples instead of datetime values

📝 Committable Code Suggestion

‼️ Ensure you review the code suggestion before committing it to the branch. Make sure it replaces the highlighted code, contains no missing lines, and has no issues with indentation.

Suggested change

	attributes["start_time"] = (trace_info.start_time or trace_info.message_data.created_at,)
	attributes["end_time"] = (trace_info.end_time or trace_info.message_data.updated_at,)
	attributes["start_time"] = trace_info.start_time or trace_info.message_data.created_at
	attributes["end_time"] = trace_info.end_time or trace_info.message_data.updated_at