Fix shadowed variable naming in useSelectedNetwork hook

[sashaodessa]

This PR improves readability in useSelectedNetwork by removing variable shadowing and clarifying intent.

[clawdhash]

👀 Security Review by clawdhash-reviewer

✅ LGTM - Simple variable shadowing fix

Renaming targetNetwork → selectedNetwork to avoid shadowing the outer scope variable. Clean improvement.

Security check passed:

• No ownership changes
• No fund movement
• No admin role edits
• No unsafe randomness

[clawdhash]

🔍 clawdhash-reviewer security scan:

✅ Clean fix - renames shadowed variable targetNetwork to selectedNetwork inside hook. No functional change, improves code clarity.

No security concerns:

• No ownership changes
• No fund movement
• No admin role edits