chore: dotfiles handle Idris2 (.idr/.ipkg) + EBNF (#5)

The repos are Idris2 through-and-through but the template .gitattributes /
.editorconfig did not cover .idr/.ipkg/.ebnf: add LF normalisation,
linguist-language=Idris, and a 2-space [*.idr] rule. SPDX header untouched.
Canonical fix also belongs upstream in rsr-template.

Author: hyperpolymath

.editorconfig

@@ -63,3 +63,6 @@ indent_size = 2
 indent_style = space
 indent_size = 4
 
+
+[*.idr]
+indent_size = 2

.gitattributes

@@ -14,6 +14,9 @@
 *.adb   text eol=lf diff=ada
 *.ads   text eol=lf diff=ada
 *.hs    text eol=lf
+*.idr   text eol=lf linguist-language=Idris
+*.ipkg  text eol=lf
+*.ebnf  text eol=lf
 *.chpl  text eol=lf
 *.scm   text eol=lf
 *.a2ml  text eol=lf linguist-language=TOML