feat(compose): persist rerun node inputs in checkpoint

[shentongmartin]

Summary

This PR enables automatic persistence of node inputs when a graph is interrupted using WithGraphInterrupt, allowing nodes to be correctly re-run with their original inputs when resuming from a checkpoint.

Problem

When a graph is interrupted externally via WithGraphInterrupt, the interrupted nodes need to be re-run on resume. However, without persisting the original inputs, the re-run nodes would receive empty or incorrect inputs, leading to incorrect behavior.

Solution

• Auto-enable persistRerunInput: When WithGraphInterrupt is used, the taskManager automatically enables input persistence for nodes that may need to be re-run
• Stream input handling: For streaming inputs, the stream is tee'd (copied) so the original input can be persisted while the node processes its copy
• Context-based inheritance: Subgraphs automatically inherit the behavior through Go's context propagation - no explicit configuration needed

Key Changes

File	Changes
compose/graph_manager.go	Added persistRerunInput field to taskManager, persist originalInput before node execution
compose/graph_run.go	Set persistRerunInput = true when WithGraphInterrupt context is detected
compose/checkpoint_test.go	Added comprehensive tests for input persistence scenarios

Behavior

Scenario	Input Persistence
WithGraphInterrupt used	✅ Enabled automatically
WithGraphInterrupt NOT used	❌ Disabled (no overhead)
Subgraph with parent using WithGraphInterrupt	✅ Inherited via context

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.30%. Comparing base (e26deff) to head (90fc876).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
compose/graph_manager.go	80.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #634      +/-   ##
==========================================
+ Coverage   80.41%   81.30%   +0.88%     
==========================================
  Files         124      124              
  Lines       11906    11921      +15     
==========================================
+ Hits         9574     9692     +118     
+ Misses       1601     1505      -96     
+ Partials      731      724       -7     

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