chore: support PFX filetype in attachment uploads (#14456)

# Pull Request Template

## Description

This PR expands the default upload rules to support PFX certificate
files (`application/x-pkcs12`, `application/pkcs12`, `.pfx`) across
private notes, Website, Email, and Telegram channels.

Also adds `.xls` / `.xlsx` extension fallbacks for cases where browsers
upload Excel files with an empty or generic MIME type.

### Utils Repo PR: https://github.com/chatwoot/utils/pull/61

Fixes
https://linear.app/chatwoot/issue/CW-7085/support-more-file-types-in-private-notes-and-in-app

## Type of change

- [x] New feature (non-breaking change which adds functionality)

## How Has This Been Tested?

### Screenshots
<img width="330" height="218" alt="image"
src="https://github.com/user-attachments/assets/80823250-893e-4509-adb9-61f845359151"
/>



## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [ ] 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
- [ ] 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

---------

Co-authored-by: aakashb95 <aakashbakhle@gmail.com>

pnpm-lock.yaml

@@ -29,8 +29,8 @@ importers:
         specifier: 1.3.13
         version: 1.3.13
       '@chatwoot/utils':
-        specifier: ^0.0.52
-        version: 0.0.52
+        specifier: ^0.0.55
+        version: 0.0.55
       '@formkit/core':
         specifier: ^1.7.2
         version: 1.7.2
@@ -462,8 +462,8 @@ packages:
   '@chatwoot/prosemirror-schema@1.3.13':
     resolution: {integrity: sha512-T6FBUinMJbwDCD7975g8M/Tsn2+G3O2pTGIXdcLkMRpbAAC6mVdl4ZcZektlt5y/PVmPVqNHPsfee1XB/C3vAw==}
 
-  '@chatwoot/utils@0.0.52':
-    resolution: {integrity: sha512-e57uVqyVW4tj1gql4YJPNMykqMJPkETn5Y9AmHdhc6Y7oxDXfRXBq27fZrrDadLkZdn5RYVCZjfIhXOumyYv2Q==}
+  '@chatwoot/utils@0.0.55':
+    resolution: {integrity: sha512-8G6HYQe1ZEYfJEsSYfDVvE+uhf98JDRjtGlpB+bzMko+yltbrk4yACSo/ImC3jSaJ6K8yPTSjJToSRmsQbL2iQ==}
     engines: {node: '>=10'}
 
   '@codemirror/commands@6.7.0':
@@ -5011,7 +5011,7 @@ snapshots:
       prosemirror-utils: 1.2.2(prosemirror-model@1.22.3)(prosemirror-state@1.4.3)
       prosemirror-view: 1.34.1
 
-  '@chatwoot/utils@0.0.52':
+  '@chatwoot/utils@0.0.55':
     dependencies:
       date-fns: 2.30.0