refactor(config): default icons to ascii (#55)

* refactor(config): default icons to ascii

Problem: default icons used unicode characters (○, ✓, ●, ▸, ·, ↺)
which render poorly in some terminals and font configurations.

Solution: replace defaults with ascii equivalents (-, x, !, >, ., ~).
Users can still override to unicode or nerd font icons via config.

* ci: ignore library type checking

scripts/demo-init.lua

@@ -4,15 +4,6 @@ vim.fn.mkdir(tmpdir, 'p')
 
 vim.g.pending = {
   data_path = tmpdir .. '/tasks.json',
-  icons = {
-    pending = '○',
-    done = '✓',
-    priority = '●',
-    header = '▸',
-    due = '·',
-    recur = '↺',
-    category = '#',
-  },
 }
 
 local store = require('pending.store')