Add issues #16–#23

#16 multiline shell commands
#17 _ scope (global vs local)
#18 path expansion (~)
#19 nested commands trigger prompt2
#20 simplify backtick return value
#21 prompt redesign
#22 implicit interactive commands (drop ! prefix)
#23 general cleanup and refactor

issues/20-backtick-return-value.md

@@ -0,0 +1,30 @@
+# 20 — Simplify backtick return value
+
+**Status:** open
+
+Currently backtick expressions return a table `{code, stdout, stderr}`, requiring verbose access:
+
+```lua
+!echo ${`ls`.stdout}
+```
+
+This is explicit but noisy for the common case. Consider making backticks return stdout directly, with the full result table still available via `_`:
+
+```lua
+-- backtick returns stdout string directly
+local files = `ls`
+
+-- full result still available in _
+print(_.code)
+print(_.stderr)
+```
+
+## Considerations
+
+- This would be a breaking change to current backtick semantics
+- The table is still useful when you need exit code or stderr
+- Could we return multiple values? `stdout, result_table = \`cmd\``
+- How does this interact with pipelines where you chain results?
+
+- This would unify the interface/behaviour of backticks and ! commands, both set the majority of their data to `_`
+- Main difference is where do they output their stdout & stderr