chore: drop accidentally-committed draft issue bodies

`be44687f` swept two local draft issue bodies (`.issue-black76-greeks.md`,
`.issue-gk-greeks.md`) into the commit via `git add -A`. They were
working-tree scratch for the deferred Black-76 / Garman-Kohlhagen
Greeks follow-up issues and should not ship. Remove them and add
`.issue-*.md` / `.pr-*.md` patterns at the repo root to `.gitignore`
so this doesn't recur.

Author: joaquinbejar

.gitignore

@@ -31,3 +31,7 @@ src/.DS_Store
 
 # Local development examples
 /examples/Local/
+
+# Local draft issue / PR bodies kept at the repo root
+/.issue-*.md
+/.pr-*.md