chore: insert resolved variable value in reply editor (#14921)

# Pull Request Template

## Description

This PR makes reply editor variables insert their resolved value (for
example, the contact's name) instead of the raw `{{contact.name}}`
placeholder, matching canned response behavior. This works both when
picking a variable from the `{{` menu and when an agent manually types
out `{{contact.name}}` — it resolves the moment the closing `}}` is
typed.

If a variable has no value, the `{{placeholder}}` is kept so the backend
can still resolve it when the message is sent. Private notes are left
untouched.

For safety, a resolved value that itself contains Liquid syntax `({{ }}`
or `{% %})` also keeps its placeholder, so customer-controlled fields
can never inject Liquid into the outgoing message.

Fixes
https://linear.app/chatwoot/issue/CW-7528/reply-editor-inserts-variable-placeholder-instead-of-the-value

## Type of change

- [x] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

1. Open a conversation and add a reply.
2. Type `{{` and pick a variable that has a value (e.g. Contact name) →
it inserts the actual value.
3. Manually type `{{contact.name}}` and close the braces → it
auto-resolves to the value.
4. Insert/type a variable with no value → the `{{placeholder}}` stays;
confirm it resolves correctly on send.
5. Repeat in a private note → placeholders are left as-is.


## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

pnpm-lock.yaml

@@ -183,6 +183,9 @@ importers:
       prosemirror-commands:
         specifier: ^1.7.1
         version: 1.7.1
+      prosemirror-inputrules:
+        specifier: ^1.4.0
+        version: 1.4.0
       prosemirror-schema-list:
         specifier: ^1.5.1
         version: 1.5.1
@@ -9037,7 +9040,7 @@ snapshots:
   prosemirror-state@1.4.3:
     dependencies:
       prosemirror-model: 1.22.3
-      prosemirror-transform: 1.10.0
+      prosemirror-transform: 1.12.0
       prosemirror-view: 1.34.1
 
   prosemirror-tables@1.5.0:
@@ -9065,7 +9068,7 @@ snapshots:
     dependencies:
       prosemirror-model: 1.22.3
       prosemirror-state: 1.4.3
-      prosemirror-transform: 1.10.0
+      prosemirror-transform: 1.12.0
 
   proto-list@1.2.4: {}