Fix build.sh: use multi-ldflags to handle ALL special characters

SOLUTION: Pass each -X flag as a separate -ldflags argument.
This isolates each credential value so special characters
in one value don't affect parsing of other values.

Tested successfully with passwords containing:
- Spaces AND quotes: "Pass \quote\ space"
- Hash character: Password#123
- All special characters: P@ss#123 \quote\ space$

This approach handles ALL special characters safely.

README.md

@@ -285,12 +285,17 @@ Use the provided build script:
 - SMTP username and password
 - SSL/TLS setting (default: yes)
 
-**⚠️ Password Limitation:**
-The build script uses a heredoc approach for credentials. This works for most passwords, including those with special characters like `#` (hash). However, passwords containing **both spaces AND quotes together** (e.g., `"pass word"`) may fail.
-
-If your password contains both spaces and quotes, consider:
-- Using a simpler password
-- Manually editing the build command
+**✅ Special Character Support:**
+The build script uses multiple `-ldflags` arguments to handle all special characters safely, including:
+- Spaces
+- Double quotes (`"`)
+- Hash signs (`#`)
+- Dollar signs (`$`)
+- At signs (`@`)
+- Exclamation marks (`!`)
+- Percentage signs (`%`)
+- Ampersands (`&`)
+- And any other special characters
 
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