feat: enhance build configuration with C++ standard support and variable substitution

- Added `cxx_standard` field to the build configuration for specifying C++ standards.
- Updated documentation to reflect new `cxx_standard` and variable substitution capabilities in `cflags`, `ldflags`, and `include`.
- Implemented logic to handle C++ standard flags in the build process.
- Modified object file naming to include source file extensions.
- Updated various builder modules to support new language parsing logic.
- Introduced issue and feature request templates for better community engagement.

docs/configuration/package-section.md

@@ -4,9 +4,12 @@
 
 ```toml
 [package]
-name = "my-app"
-version = "0.1.0"
-type = "app"
+name        = "my-app"
+version     = "0.1.0"
+type        = "app"
+description = "My application"
+author      = "John Doe"
+license     = "MIT"
 ```
 
 ## Fields
@@ -14,6 +17,15 @@ type = "app"
 - `name` (string, required): used as output artifact base name.
 - `version` (string, required): used in `dcr.lock` project entry.
 - `type` (string, optional): project type (`app`, `lib`, `none`).
+- `description` (string, optional): human-readable project description.
+- `author` (string, optional): single author name.
+- `authors` (array of strings, optional): list of authors.
+- `license` (string, optional): project license identifier (e.g. `MIT`, `GPL-3.0-or-later`).
+- `homepage` (string, optional): project homepage URL.
+- `repository` (string, optional): source repository URL.
+- `readme` (string, optional): path to README file.
+- `keywords` (array of strings, optional): project keywords.
+- `categories` (array of strings, optional): project categories.
 
 ## Notes