fix: reset result counter per username scan (#2990)

[Dev9269]

Closes #2990

Problem: notify.py used a module-level globvar = 0 to count claimed results. The single QueryNotifyPrint instance persists across all username scans, and the global was never reset, so the "Search completed with X results" line showed a cumulative total when scanning multiple usernames.

Fix:

• Replaced the module global with an instance attribute self._count, initialized in __init__.
• Reset self._count = 0 in start() (called once per username scan in sherlock()).
• countResults() now increments self._count instead of the global.
• finish() reads self._count directly instead of doing the fragile countResults() - 1 increment-then-compensate dance.

Behavior is unchanged for single-username scans and correct per-username for multi-username scans.