When using inlineButtons="dm" or "group" scope, the validation check
resolveTelegramTargetChatType() failed for numeric chat IDs because
normalizeTelegramMessagingTarget() adds a "telegram:" prefix during
target resolution.
For example, target "5232990709" becomes "telegram:5232990709" after
normalization, but the regex /^-?\d+$/ expects a pure numeric string.
The fix strips the telegram: prefix before checking the numeric pattern.
Adds tests for resolveTelegramTargetChatType with various input formats.
