feat: implement complete tree-sitter-shellspec grammar with comprehensive testing

- Add full ShellSpec grammar extending tree-sitter-bash
- Support all ShellSpec constructs: Describe, Context, It, hooks, utilities
- Include Data block parsing with statements and argument styles
- Add 61 comprehensive test cases covering real-world patterns
- Implement optimized GitHub workflows with CI/CD automation
- Configure complete development tooling (linting, formatting, pre-commit)
- Add comprehensive documentation and contribution guidelines
- Optimize grammar conflicts to zero warnings
- Support editor integration for Neovim, VS Code, Emacs

Breaking Changes:
- Initial release, no previous API to break

BREAKING CHANGE: Initial implementation of tree-sitter-shellspec grammar

# Conflicts:
#	.github/workflows/codeql.yml
#	.github/workflows/pr-lint.yml
#	.pre-commit-config.yaml

# Conflicts:
#	.github/workflows/pr-lint.yml

# Conflicts:
#	.github/workflows/pr-lint.yml

test/spec/18.const_directive_spec.sh

@@ -0,0 +1,29 @@
+#shellcheck shell=sh
+
+%const NAME: value
+# shellcheck disable=SC2288
+% MAJOR_VERSION: "${SHELLSPEC_VERSION%%.*}"
+# % OK: "$(echo_ok)" # echo_ok not found
+
+# %const (% is short hand) directive is define constant value.
+# The characters that can be used for variable name is upper capital, number
+# and underscore only. It can not be define inside of the example group or
+# the example.
+#
+# The timing of evaluation of the value is the specfile translation process.
+# So you can access shellspec variables, but you can not access variable or
+# function in the specfile.
+#
+# This feature assumed use with conditional skip. The conditional skip may runs
+# outside of the examples. As a result, sometime you may need variables defined
+# outside of the examples.
+
+Describe '%const directive'
+  echo_ok() { echo ok; }
+  version_check() { [ "$MAJOR_VERSION" -lt "$1" ]; }
+
+  Skip if 'too old version' version_check 1
+  Example
+    The variable NAME should eq 'value'
+  End
+End