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

spec/icons_spec.lua

@@ -15,23 +15,23 @@ describe('icons', function()
 
   it('has default icon values', function()
     local icons = config.get().icons
-    assert.equals('○', icons.pending)
-    assert.equals('✓', icons.done)
-    assert.equals('●', icons.priority)
-    assert.equals('▸', icons.header)
-    assert.equals('·', icons.due)
-    assert.equals('↺', icons.recur)
+    assert.equals('-', icons.pending)
+    assert.equals('x', icons.done)
+    assert.equals('!', icons.priority)
+    assert.equals('>', icons.header)
+    assert.equals('.', icons.due)
+    assert.equals('~', icons.recur)
     assert.equals('#', icons.category)
   end)
 
   it('allows overriding individual icons', function()
-    vim.g.pending = { icons = { pending = '-', done = 'x' } }
+    vim.g.pending = { icons = { pending = '○', done = '✓' } }
     config.reset()
     local icons = config.get().icons
-    assert.equals('-', icons.pending)
-    assert.equals('x', icons.done)
-    assert.equals('●', icons.priority)
-    assert.equals('▸', icons.header)
+    assert.equals('○', icons.pending)
+    assert.equals('✓', icons.done)
+    assert.equals('!', icons.priority)
+    assert.equals('>', icons.header)
   end)
 
   it('allows overriding all icons', function()