chore: update s2 sdk

[sgbalogh]

Also adds example on running against s2-lite

[greptile-apps]

Greptile Summary

This PR migrates from the legacy streamstore SDK to the newer s2-sdk (v0.23.0+) and adds documentation for running against s2-lite.

Key changes:

• Replaced streamstore::Client with s2_sdk::S2 for client initialization
• Updated type imports: BasinName, StreamName, ReadInput, ReadBatch, etc.
• Migrated error handling from tonic::Code to S2Error variants with proper classification of definite vs indefinite failures
• Adapted read API: ReadOutput::Batch → ReadBatch, handling tail position through batch.tail field
• Improved hash computation flow by introducing GeneratedBatch struct to pass last_xxh3 explicitly
• Added comprehensive example in README for running against local s2-lite instance

Issues found:

• Typo in README heading: "aginst" instead of "against"
• Minor formatting issue: extra space before else in history.rs:542

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The SDK migration is comprehensive and well-executed with proper error handling updates, type migrations, and API adaptations. Only minor cosmetic issues (typo and formatting) were found that don't affect functionality
• No files require special attention - the migration is straightforward and properly handles all API changes

Important Files Changed

Filename	Overview
README.md	Added documentation for running against s2-lite with a typo in the heading ("aginst" should be "against")
rust/s2-verification/Cargo.toml	Updated dependencies: replaced streamstore with s2-sdk >=0.23.0, removed tonic, bumped version to 0.2.0
rust/s2-verification/src/bin/collect-history.rs	Migrated from streamstore SDK to s2-sdk: updated types, error handling, and client initialization patterns
rust/s2-verification/src/history.rs	Updated SDK types and error handling: adapted read stream handling for new ReadBatch API, improved error classification logic with minor formatting issue

Sequence Diagram

sequenceDiagram
    participant App as collect-history
    participant SDK as s2-sdk (new)
    participant S2 as S2 Service
    
    Note over App,S2: SDK Migration Flow
    
    App->>SDK: S2::new(config)
    SDK-->>App: S2 client instance
    
    App->>SDK: s2.basin(basin_name)
    SDK-->>App: Basin client
    
    App->>SDK: basin.stream(stream_name)
    SDK-->>App: S2Stream
    
    App->>S2: create_stream(CreateStreamInput)
    alt Stream already exists
        S2-->>App: S2Error::Server(resource_already_exists)
    else Stream created
        S2-->>App: Success
    end
    
    App->>S2: check_tail()
    S2-->>App: Position
    
    App->>S2: read(ReadInput)
    alt Stream has data
        S2-->>App: ReadBatch with records
        Note over App: Compute xxh3 hash, rectify tail
    else Stream empty
        S2-->>App: S2Error::ReadUnwritten
    end
    
    loop For each concurrent client
        App->>SDK: S2::new(config)
        SDK-->>App: New client instance
        App->>SDK: basin.stream(stream_name)
        SDK-->>App: S2Stream
        
        loop num_ops_per_client
            alt Append operation
                App->>S2: append(AppendInput)
                alt Success
                    S2-->>App: AppendAck
                else Validation/Condition error
                    S2-->>App: S2Error (definite failure)
                else Side-effect error
                    S2-->>App: S2Error (indefinite failure)
                end
            else Read operation
                App->>S2: read_session(ReadInput)
                S2-->>App: Streaming<ReadBatch>
            else CheckTail operation
                App->>S2: check_tail()
                S2-->>App: Position
            end
        end
    end
    
    Note over App: Write history to JSONL file

Loading

[greptile-apps]

_{4 files reviewed, 2 comments}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

syntax: typo: "aginst" should be "against"

Suggested change

	## Running aginst `s2-lite`
	## Running against `s2-lite`

Prompt To Fix With AI

This is a comment left during a code review.
Path: README.md
Line: 132:132

Comment:
**syntax:** typo: "aginst" should be "against"

```suggestion
## Running against `s2-lite`
```

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

style: formatting: extra space before else

Suggested change

	}
	}

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review.
Path: rust/s2-verification/src/history.rs
Line: 542:542

Comment:
**style:** formatting: extra space before `else` 

```suggestion
                }
```

<sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub>

How can I resolve this? If you propose a fix, please make it concise.