Linux/FreeBSD: Prevent mounting volumes on system directories and PATH (CVE-2025-23021, reported by SivertPL @__tfr)

Added security checks to prevent mounting VeraCrypt volumes on system directories (like /usr/bin) or directories in the user's PATH, which could theoretically allow execution of malicious binaries instead of legitimate system binaries.

Key changes:
- Block mounting on protected system directories (/usr, /bin, /lib, etc.)
  This restriction cannot be overridden
- Block mounting on directories present in user's PATH environment variable
  This can be overridden with --allow-insecure-mount flag
- Add visual warnings (red border, "[INSECURE MODE]") when mounting on PATH directories is allowed
- Handle symlinks properly when checking paths
- Add new error messages for blocked mount points

To override PATH-based restrictions only (system directories remain protected):
veracrypt --allow-insecure-mount [options] volume mountpoint

Security Impact: Low to Medium
The attack requires either:
- User explicitly choosing a system directory as mount point instead of using VeraCrypt's default mount points
- Or attacker having both filesystem access to modify favorites configuration AND knowledge of the volume password
Default mount points are not affected by this vulnerability.

Security: CVE-2025-23021

Translations/Language.it.xml

@@ -1641,6 +1641,9 @@
     <entry lang="it" key="ERR_XTS_MASTERKEY_VULNERABLE">ATTENZIONE: La chiave master del volume è vulnerabile a un attacco che compromette la sicurezza dei dati.\n\nSi prega di creare un nuovo volume e trasferire i dati in esso.</entry>
     <entry lang="it" key="ERR_SYSENC_XTS_MASTERKEY_VULNERABLE">ATTENZIONE: La chiave master del sistema crittografato è vulnerabile a un attacco che compromette la sicurezza dei dati.\nSi prega di decrittografare la partizione/unità di sistema e poi ricrittografarla.</entry>
     <entry lang="it" key="ERR_XTS_MASTERKEY_VULNERABLE_SHORT">ATTENZIONE: La chiave master del volume ha una vulnerabilità di sicurezza.</entry>
+    <entry lang="en" key="MOUNTPOINT_BLOCKED">ERROR: The volume mount point is blocked because it overrides a protected system directory.\n\nPlease choose a different mount point.</entry>
+    <entry lang="en" key="MOUNTPOINT_NOTALLOWED">ERROR: The volume mount point is not allowed because it overrides a directory that is part of the PATH environment variable.\n\nPlease choose a different mount point.</entry>
+    <entry lang="en" key="INSECURE_MODE">[INSECURE MODE]</entry>
   </localization>
   <xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
     <xs:element name="VeraCrypt">