feat: reorganize examples and add signature support to JobBuilder

- Reorganized examples into osiris/, sal/, and utils/ folders
- Moved hardcoded scripts to separate .rhai files
- Added signature() method to JobBuilder for job signing
- Updated OSIRIS context to use block_in_place instead of runtime
- Removed runtime field from OsirisContext
- Added typed save() methods for Note and Event objects
- Updated all examples to use new structure and APIs

examples/utils/README.md

@@ -0,0 +1,20 @@
+# Utility Examples
+
+This directory contains utility examples for working with the runner system.
+
+## sign_job
+
+Demonstrates how to:
+- Create a job with signatories
+- Sign the job with secp256k1 private keys
+- Verify the signatures
+
+### Usage
+
+```bash
+cargo run --example sign_job --features crypto
+```
+
+### Requirements
+
+The `crypto` feature must be enabled to use cryptographic signing functionality.