Update project issues: resolve #02-#04, add #08-#10

Mark issues #02 (backtick lexing/parsing), #03 (command execution
runtime), and #04 (argv parsing) as resolved. Add new issues for
configuration (#08), programmable prompt (#09), and interactive
command execution (#10).

issues/08-configuration.md

@@ -0,0 +1,29 @@
+# 08 — Configuration support
+
+**Status:** open
+
+Users should be able to programmatically configure the shell at startup.
+
+## Config location
+
+- `~/.config/lush/config` — main config file (Lua script)
+- `~/.config/lush/config.d/` — drop-in directory, files sourced in lexicographic order
+
+## What can be configured
+
+- **Prompt** — see #09
+- **Aliases** — command aliases (e.g. `alias("ll", "ls -l")`)
+- **Environment setup** — set/modify env vars at startup
+- **Autocompletion rules** — TBD, mechanism for registering custom completions
+
+## Startup behaviour
+
+1. If `~/.config/lush/config` exists, execute it as a Lua script
+2. If `~/.config/lush/config.d/` exists, execute each `.lua` file in lexicographic order
+3. Config files run in the same Lua state as the interactive session — locals, globals, and env changes persist
+
+## Open questions
+
+- Should there be a system-wide config (`/etc/lush/config`) sourced before user config?
+- What API surface to expose for autocompletion registration?
+- Should config errors be fatal or just print a warning and continue?