fix: query tab title incorrectly shows table name after execution (#668)

[datlechin]

Summary

Fix query tab's window title changing to the executed table name, which also breaks sidebar table navigation.

Closes #668

Root Cause

updateWindowTitleAndFileState() used selectedTab?.tableName as the window title regardless of tab type. After SELECT * FROM users, tableName = "users" is set (needed for edit support), but the window title also became "users".

This caused openTableTab's window dedup check (window.title == tableName) to match the query tab, preventing new table tabs from opening.

Fix

One line: guard tableName usage on tabType == .table. Query tabs use tab.title ("Query 1") as the window title.

// Before:
windowTitle = selectedTab?.tableName ?? ...

// After:
windowTitle = (selectedTab?.tabType == .table ? selectedTab?.tableName : nil)
    ?? selectedTab?.title ?? ...

Test plan

• Execute SELECT * FROM users in query tab: window title stays "Query 1" (not "users")
• Click "users" in sidebar: opens new table tab (not switches to query tab)
• Open table tab for "users": window title shows "users"
• ER Diagram tab: window title shows "ER Diagram"
• Create Table tab: window title shows "Create Table"
• File-backed query: window title shows filename