refactor: revert module namespace from canola back to oil

Problem: the canola rename creates unnecessary friction for users
migrating from stevearc/oil.nvim — every `require('oil')` call and
config reference must change.

Solution: revert all module paths, URL schemes, autocmd groups,
highlight groups, and filetype names back to `oil`. The repo stays
`canola.nvim` for identity; the code is a drop-in replacement.

spec/regression_spec.lua

@@ -1,8 +1,8 @@
 local TmpDir = require('spec.tmpdir')
-local actions = require('canola.actions')
-local canola = require('canola')
+local actions = require('oil.actions')
+local oil = require('oil')
 local test_util = require('spec.test_util')
-local view = require('canola.view')
+local view = require('oil.view')
 
 describe('regression tests', function()
   local tmpdir
@@ -21,29 +21,29 @@ describe('regression tests', function()
     vim.cmd.edit({ args = { 'README.md' } })
     vim.cmd.vsplit()
     vim.cmd.edit({ args = { '%:p:h' } })
-    assert.equals('canola', vim.bo.filetype)
+    assert.equals('oil', vim.bo.filetype)
     vim.cmd.wincmd({ args = { 'p' } })
     assert.equals('markdown', vim.bo.filetype)
     vim.cmd.edit({ args = { '%:p:h' } })
-    test_util.wait_for_autocmd({ 'User', pattern = 'CanolaEnter' })
-    assert.equals('canola', vim.bo.filetype)
+    test_util.wait_for_autocmd({ 'User', pattern = 'OilEnter' })
+    assert.equals('oil', vim.bo.filetype)
   end)
 
   it('places the cursor on correct entry when opening on file', function()
     vim.cmd.edit({ args = { '.' } })
-    test_util.wait_for_autocmd({ 'User', pattern = 'CanolaEnter' })
-    local entry = canola.get_cursor_entry()
+    test_util.wait_for_autocmd({ 'User', pattern = 'OilEnter' })
+    local entry = oil.get_cursor_entry()
     assert.not_nil(entry)
     assert.not_equals('README.md', entry and entry.name)
     vim.cmd.edit({ args = { 'README.md' } })
     view.delete_hidden_buffers()
-    canola.open()
-    test_util.wait_for_autocmd({ 'User', pattern = 'CanolaEnter' })
-    entry = canola.get_cursor_entry()
+    oil.open()
+    test_util.wait_for_autocmd({ 'User', pattern = 'OilEnter' })
+    entry = oil.get_cursor_entry()
     assert.equals('README.md', entry and entry.name)
   end)
 
-  it("doesn't close floating windows canola didn't open itself", function()
+  it("doesn't close floating windows oil didn't open itself", function()
     local winid = vim.api.nvim_open_win(vim.fn.bufadd('README.md'), true, {
       relative = 'editor',
       row = 1,
@@ -51,21 +51,21 @@ describe('regression tests', function()
       width = 100,
       height = 100,
     })
-    canola.open()
+    oil.open()
     vim.wait(10)
-    canola.close()
+    oil.close()
     vim.wait(10)
     assert.equals(winid, vim.api.nvim_get_current_win())
   end)
 
-  it("doesn't close splits on canola.close", function()
+  it("doesn't close splits on oil.close", function()
     vim.cmd.edit({ args = { 'README.md' } })
     vim.cmd.vsplit()
     local winid = vim.api.nvim_get_current_win()
     local bufnr = vim.api.nvim_get_current_buf()
-    canola.open()
+    oil.open()
     vim.wait(10)
-    canola.close()
+    oil.close()
     vim.wait(10)
     assert.equals(2, #vim.api.nvim_tabpage_list_wins(0))
     assert.equals(winid, vim.api.nvim_get_current_win())
@@ -73,24 +73,24 @@ describe('regression tests', function()
   end)
 
   it('Returns to empty buffer on close', function()
-    canola.open()
-    test_util.wait_for_autocmd({ 'User', pattern = 'CanolaEnter' })
-    canola.close()
-    assert.not_equals('canola', vim.bo.filetype)
+    oil.open()
+    test_util.wait_for_autocmd({ 'User', pattern = 'OilEnter' })
+    oil.close()
+    assert.not_equals('oil', vim.bo.filetype)
     assert.equals('', vim.api.nvim_buf_get_name(0))
   end)
 
   it('All buffers set nomodified after save', function()
     tmpdir:create({ 'a.txt' })
-    vim.cmd.edit({ args = { 'canola://' .. vim.fn.fnamemodify(tmpdir.path, ':p') } })
+    vim.cmd.edit({ args = { 'oil://' .. vim.fn.fnamemodify(tmpdir.path, ':p') } })
     local first_dir = vim.api.nvim_get_current_buf()
-    test_util.wait_for_autocmd({ 'User', pattern = 'CanolaEnter' })
+    test_util.wait_for_autocmd({ 'User', pattern = 'OilEnter' })
     test_util.feedkeys({ 'dd', 'itest/<esc>', '<CR>' }, 10)
     vim.wait(1000, function()
       return vim.bo.modifiable
     end, 10)
     test_util.feedkeys({ 'p' }, 10)
-    canola.save({ confirm = false })
+    oil.save({ confirm = false })
     vim.wait(1000, function()
       return vim.bo.modifiable
     end, 10)
@@ -102,11 +102,11 @@ describe('regression tests', function()
 
   it("refreshing buffer doesn't lose track of it", function()
     vim.cmd.edit({ args = { '.' } })
-    test_util.wait_for_autocmd({ 'User', pattern = 'CanolaEnter' })
+    test_util.wait_for_autocmd({ 'User', pattern = 'OilEnter' })
     local bufnr = vim.api.nvim_get_current_buf()
     vim.cmd.edit({ bang = true })
-    test_util.wait_for_autocmd({ 'User', pattern = 'CanolaEnter' })
-    assert.are.same({ bufnr }, require('canola.view').get_all_buffers())
+    test_util.wait_for_autocmd({ 'User', pattern = 'OilEnter' })
+    assert.are.same({ bufnr }, require('oil.view').get_all_buffers())
   end)
 
   it('can copy a file multiple times', function()
@@ -126,8 +126,8 @@ describe('regression tests', function()
 
   it('can open files from floating window', function()
     tmpdir:create({ 'a.txt' })
-    canola.open_float(tmpdir.path)
-    test_util.wait_for_autocmd({ 'User', pattern = 'CanolaEnter' })
+    oil.open_float(tmpdir.path)
+    test_util.wait_for_autocmd({ 'User', pattern = 'OilEnter' })
     actions.select.callback()
     vim.wait(1000, function()
       return vim.fn.expand('%:t') == 'a.txt'