Eliminate duplicated _escape_markdown method

[Copilot]

Closes: #(issue number)

Description

The _escape_markdown method had identical implementations in both TelegramNotifier and TelegramEmailNotifier classes.

Changes:

• Removed duplicate method from TelegramEmailNotifier (36 lines)
• Renamed _escape_markdown to escape_markdown in TelegramNotifier (now public API)
• Updated TelegramEmailNotifier to delegate to self.notifier.escape_markdown()
• Added comprehensive docstring with Args/Returns sections

Before:

class TelegramEmailNotifier:
    def _format_email_notification(...):
        return f"*From:* {self._escape_markdown(email.sender)}"
    
    def _escape_markdown(self, text: str) -> str:
        # 24 lines of duplication...

After:

class TelegramEmailNotifier:
    def _format_email_notification(...):
        return f"*From:* {self.notifier.escape_markdown(email.sender)}"
    
    # Method removed - delegates to TelegramNotifier

Net -26 lines. Single source of truth for Telegram markdown escaping.

Tradeoffs

Made escape_markdown public to maintain proper encapsulation rather than accessing a private method across classes. This is the correct design but expands the public API surface.

Alternatives

Considered creating a shared utility module, but the method is Telegram-specific and belongs in TelegramNotifier. Current solution leverages existing composition relationship between the classes.

Original prompt

Find and refactor duplicated code

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