feat: Add herodo package to workspace

- Added the `herodo` package to the workspace.
- Updated the MONOREPO_CONVERSION_PLAN.md to reflect
  the completion of the herodo package conversion.
- Updated README.md and build_herodo.sh to reflect the
  new package structure.
- Created herodo/Cargo.toml, herodo/README.md,
  herodo/src/main.rs, herodo/src/lib.rs, and
  herodo/tests/integration_tests.rs and
  herodo/tests/unit_tests.rs.

herodo/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "herodo"
+version = "0.1.0"
+edition = "2021"
+authors = ["PlanetFirst <info@incubaid.com>"]
+description = "Herodo - A Rhai script executor for SAL (System Abstraction Layer)"
+repository = "https://git.threefold.info/herocode/sal"
+license = "Apache-2.0"
+keywords = ["rhai", "scripting", "automation", "sal", "system"]
+categories = ["command-line-utilities", "development-tools"]
+
+[[bin]]
+name = "herodo"
+path = "src/main.rs"
+
+[dependencies]
+# Core dependencies for herodo binary
+env_logger = "0.11.8"
+rhai = { version = "1.12.0", features = ["sync"] }
+
+# SAL library for Rhai module registration
+sal = { path = ".." }
+
+[dev-dependencies]
+tempfile = "3.5"