docs: update docs (#43)

- macOS, Linux badge and AI suggestions showcase in README
- Update user guide and docs for development

docs/dev/development.md

@@ -0,0 +1,50 @@
+# Development guide
+
+This document outlines the development workflow, build system, and coding conventions for contributors working on the Iris codebase.
+
+## Environment setup
+
+Clone the repository and sync dependencies:
+
+```bash
+git clone https://github.com/versenilvis/iris.git
+cd iris
+go mod tidy
+```
+
+## Modular `just` command runner
+
+We use `just` as our primary command runner. Recipes are organized into modular files under `justfiles/`:
+
+- `justfiles/build.just` (`[build]` group): `build`, `optimized-build`, `build-release <version>`
+- `justfiles/dev.just` (`[dev]` group): `run`, `config-init`, `reload`, `copy`
+- `justfiles/test.just` (`[test]` group): `test`, `lint`, `analyze` (alias `ana`)
+- `justfiles/gen.just` (`[gen]` group): `gen-docs`
+- `justfiles/pkg.just` (`[pkg]` group): `pkg`
+- `justfiles/debug.just` (`[debug]` group): `debug`, `debug-update`, `debug-notify`, `debug-install`
+
+Run `just -l` to quickly view all available recipes organized by group.
+
+## Building and testing
+
+### Rapid hot-reload
+
+```bash
+just reload
+```
+
+### Running unit tests
+
+```bash
+just test
+# OR
+go test -v ./...
+```
+
+### Running linter
+
+```bash
+just lint
+# OR
+golangci-lint run ./...
+```