fix: add explicit remove assignment actions to macros and automations (#12172)

This updates macros and automations so agents can explicitly remove
assigned agents or teams, while keeping the existing `Assign -> None`
flow working for backward compatibility.

Fixes: #7551
Closes: #7551

## Why
The original macro change exposed unassignment only through `Assign ->
None`, which made macros behave differently from automations and left
the explicit remove actions inconsistent across the product. This keeps
the lower-risk compatibility path and adds the explicit remove actions
requested in review.

## What this change does
- Adds `Remove Assigned Agent` and `Remove Assigned Team` as explicit
actions in macros.
- Adds the same explicit remove actions in automations.
- Keeps `Assign Agent -> None` and `Assign Team -> None` working for
existing behavior and stored payloads.
- Preserves backward compatibility for existing macro and automation
execution payloads.
- Downmerges the latest `develop` and resolves the conflicts while
keeping both the new remove actions and current `develop` behavior.

## Validation
- Verified both remove actions are available and selectable in the macro
editor.
- Verified both remove actions are available and selectable in the
automation builder.
- Applied a disposable macro with `Remove Assigned Agent` and `Remove
Assigned Team` on a real conversation and confirmed both fields were
cleared.
- Applied a disposable macro with `Assign Agent -> None` and `Assign
Team -> None` on a real conversation and confirmed both fields were
still cleared.

app/javascript/dashboard/composables/spec/useMacros.spec.js

@@ -119,24 +119,30 @@ describe('useMacros', () => {
     const { getMacroDropdownValues } = useMacros();
     expect(getMacroDropdownValues('add_label')).toHaveLength(mockLabels.length);
     expect(getMacroDropdownValues('assign_team')).toHaveLength(
-      mockTeams.length
-    );
+      mockTeams.length + 1
+    ); // +1 for "None"
     expect(getMacroDropdownValues('assign_agent')).toHaveLength(
-      mockAgents.length + 1
-    ); // +1 for "Self"
+      mockAgents.length + 2
+    ); // +2 for "None" and "Self"
   });
 
-  it('returns teams for assign_team and send_email_to_team types', () => {
+  it('returns teams with "None" option for assign_team and teams only for send_email_to_team', () => {
     const { getMacroDropdownValues } = useMacros();
-    expect(getMacroDropdownValues('assign_team')).toEqual(mockTeams);
+    const assignTeamResult = getMacroDropdownValues('assign_team');
+    expect(assignTeamResult[0]).toEqual({
+      id: 'nil',
+      name: 'AUTOMATION.NONE_OPTION',
+    });
+    expect(assignTeamResult.slice(1)).toEqual(mockTeams);
     expect(getMacroDropdownValues('send_email_to_team')).toEqual(mockTeams);
   });
 
-  it('returns agents with "Self" option for assign_agent type', () => {
+  it('returns agents with "None" and "Self" options for assign_agent type', () => {
     const { getMacroDropdownValues } = useMacros();
     const result = getMacroDropdownValues('assign_agent');
-    expect(result[0]).toEqual({ id: 'self', name: 'Self' });
-    expect(result.slice(1)).toEqual(mockAgents);
+    expect(result[0]).toEqual({ id: 'nil', name: 'AUTOMATION.NONE_OPTION' });
+    expect(result[1]).toEqual({ id: 'self', name: 'Self' });
+    expect(result.slice(2)).toEqual(mockAgents);
   });
 
   it('returns formatted labels for add_label and remove_label types', () => {
@@ -172,8 +178,11 @@ describe('useMacros', () => {
 
     const { getMacroDropdownValues } = useMacros();
     expect(getMacroDropdownValues('add_label')).toEqual([]);
-    expect(getMacroDropdownValues('assign_team')).toEqual([]);
+    expect(getMacroDropdownValues('assign_team')).toEqual([
+      { id: 'nil', name: 'AUTOMATION.NONE_OPTION' },
+    ]);
     expect(getMacroDropdownValues('assign_agent')).toEqual([
+      { id: 'nil', name: 'AUTOMATION.NONE_OPTION' },
       { id: 'self', name: 'Self' },
     ]);
   });