Seed from go-template-repo, renamed to simplexcalc

The template's files at a77fd30, without its history or LICENSE, after
script/rename simplexcalc.

Model: opus-5-5

.gitignore

@@ -0,0 +1,23 @@
+/bin/
+/data/
+.env
+.env.*
+*.key
+*.pem
+*.db
+*.sqlite
+*.sqlite3
+.DS_Store
+*~
+*.swp
+
+# Editor and assistant tooling directories. These are per-developer state and
+# never belong in the repository; documentation for contributors, human or
+# otherwise, lives in AGENTS.md.
+.idea/
+.vscode/
+.claude/
+.cursor/
+.aider*
+.continue/
+.windsurf/