Rename unittest_file item to unittest

- constants.py: TYPE_UNITTEST_FILE → TYPE_UNITTEST, cmd "unittest_file" → "unittest"
- All Python files updated: test_item_unittest.py, test_set.py, test_init.py,
  terminal.py, report_export_txt.py, test_tree_item.py
- All .tum files updated (examples, validation, doc)
- Sphinx doc: unittest_file_test_item.rst → unittest_test_item.rst,
  all references updated

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

doc/examples/dummy/cpt/endurance.tum

@@ -1,4 +1,4 @@
 
-  - unittest_file:
+  - unittest:
         name: Test 5
         test_file: dummy.py

doc/examples/dummy/cpt/temperature.tum

@@ -3,7 +3,7 @@ sequence: &endurance_test
     !include endurance.tum
 
 sequence:
-    - unittest_file:
+    - unittest:
         name: Test 3
         test_file: dummy.py
         test_method: test_01_pass
@@ -11,6 +11,6 @@ sequence:
         iterator: 10
         steps:
             *endurance_test
-    - unittest_file:
+    - unittest:
         name: Test 4
         test_file: dummy.py

doc/examples/dummy/dummy.tum

@@ -15,7 +15,7 @@ main:
                 - $(reference_1)
                 - $(reference_2)
             report_show_success: true
-        - unittest_file:
+        - unittest:
               name: Test 1
               test_file: dummy.py
               doc: |
@@ -23,7 +23,7 @@ main:
                   Voilà...
         - sleep:
             {name: Sleep between one and two, timeout: 10, dialog: true}
-        - unittest_file:
+        - unittest:
             {name: Test 2, test_file: dummy.py,execute_on_stop: true}
         - loop:
             name: Cycle Temperature

doc/examples/example_cycle.tum

@@ -14,7 +14,7 @@ main:
         key: report-key-2
         stop_on_failure: True
         steps:
-          - unittest_file:
+          - unittest:
               name: unittest item
               doc: |
                 The purpose of this unittest test item is to demonstrate
@@ -41,7 +41,7 @@ main:
               param:
                   - 123
 
-          - unittest_file:
+          - unittest:
               name: Unittest item
               test_file: dummy/dummy.py
               test_method:
@@ -98,7 +98,7 @@ main:
         name: Infine loop unittest step crashes
         stop_on_failure: True
         steps:
-          - unittest_file:
+          - unittest:
               name: Unittest item
               test_file: dummy/dummy.py
               test_method:
@@ -243,7 +243,7 @@ main:
         name: Infinite loop
         skipped: True
         steps:
-          - unittest_file:
+          - unittest:
               name: Unittest item
               test_file: dummy/dummy.py
               test_method: test_01_pass

doc/examples/example_items.tum

@@ -9,7 +9,7 @@ main:
     name: Test Sample number one
     version: 0.1
     steps:
-        - unittest_file:
+        - unittest:
             name: Unittest item
             test_file: dummy/unittest_str.py
             doc: Unittest test
@@ -88,7 +88,7 @@ main:
             name: cycle item
             iterator : 3
             steps:
-                - unittest_file:
+                - unittest:
                     name: Unittest item
                     test_file: dummy/dummy.py
                     test_method: test_01_pass
@@ -99,7 +99,7 @@ main:
                     name: cycle item
                     iterator : 3
                     steps:
-                        - unittest_file:
+                        - unittest:
                             name: Unittest item
                             test_file: dummy/dummy.py
                             test_method: test_01_pass