refactor(config): remove legacy gcal top-level config key

Problem: the gcal migration shim silently accepted vim.g.pending = { gcal
= {...} } and copied it to sync.gcal, adding complexity and a deprecated
API surface.

Solution: remove the migration block in config.get(), drop the cfg.gcal
fallback in gcal_config(), delete the two migration tests, and clean up
the vimdoc references. Callers must now use sync.gcal directly.

doc/pending.txt

@@ -631,12 +631,6 @@ Fields: ~
                          name and the value is the backend-specific config
                          table. Currently only `gcal` is built-in.
 
-    {gcal}               (table, default: nil)
-                         Legacy shorthand for `sync.gcal`. If `gcal` is set
-                         but `sync.gcal` is not, the value is migrated
-                         automatically. New configs should use `sync.gcal`
-                         instead. See |pending.GcalConfig|.
-
     {icons}              (table)                          *pending.Icons*
                          Icon characters displayed in the buffer. Fields:
                            {pending}   Uncompleted task icon. Default: '○'
@@ -881,9 +875,6 @@ Configuration: >lua
     }
 <
 
-The legacy `gcal` top-level key is still accepted and migrated automatically.
-New configurations should use `sync.gcal`.
-
                                                           *pending.GcalConfig*
 Fields: ~
     {calendar}           (string, default: 'Pendings')

lua/pending/config.lua

@@ -45,7 +45,6 @@
 ---@field debug? boolean
 ---@field keymaps pending.Keymaps
 ---@field sync? pending.SyncConfig
----@field gcal? pending.GcalConfig
 ---@field icons pending.Icons
 
 ---@class pending.config
@@ -101,10 +100,6 @@ function M.get()
   end
   local user = vim.g.pending or {}
   _resolved = vim.tbl_deep_extend('force', defaults, user)
-  if _resolved.gcal and not (_resolved.sync and _resolved.sync.gcal) then
-    _resolved.sync = _resolved.sync or {}
-    _resolved.sync.gcal = _resolved.gcal
-  end
   return _resolved
 end
 

lua/pending/sync/gcal.lua

@@ -23,7 +23,7 @@ local SCOPE = 'https://www.googleapis.com/auth/calendar'
 ---@return table<string, any>
 local function gcal_config()
   local cfg = config.get()
-  return (cfg.sync and cfg.sync.gcal) or cfg.gcal or {}
+  return (cfg.sync and cfg.sync.gcal) or {}
 end
 
 ---@return string

spec/sync_spec.lua

@@ -112,39 +112,14 @@ describe('sync', function()
     end)
   end)
 
-  describe('config migration', function()
-    it('migrates legacy gcal to sync.gcal', function()
-      config.reset()
-      vim.g.pending = {
-        data_path = tmpdir .. '/tasks.json',
-        gcal = { calendar = 'MyCalendar' },
-      }
-      local cfg = config.get()
-      assert.is_not_nil(cfg.sync)
-      assert.is_not_nil(cfg.sync.gcal)
-      assert.are.equal('MyCalendar', cfg.sync.gcal.calendar)
-    end)
-
-    it('does not overwrite explicit sync.gcal with legacy gcal', function()
-      config.reset()
-      vim.g.pending = {
-        data_path = tmpdir .. '/tasks.json',
-        gcal = { calendar = 'Legacy' },
-        sync = { gcal = { calendar = 'Explicit' } },
-      }
-      local cfg = config.get()
-      assert.are.equal('Explicit', cfg.sync.gcal.calendar)
-    end)
-
-    it('works with sync.gcal and no legacy gcal', function()
-      config.reset()
-      vim.g.pending = {
-        data_path = tmpdir .. '/tasks.json',
-        sync = { gcal = { calendar = 'NewStyle' } },
-      }
-      local cfg = config.get()
-      assert.are.equal('NewStyle', cfg.sync.gcal.calendar)
-    end)
+  it('works with sync.gcal config', function()
+    config.reset()
+    vim.g.pending = {
+      data_path = tmpdir .. '/tasks.json',
+      sync = { gcal = { calendar = 'NewStyle' } },
+    }
+    local cfg = config.get()
+    assert.are.equal('NewStyle', cfg.sync.gcal.calendar)
   end)
 
   describe('gcal module', function()