fix: skip pool stats fetching when pool mining is disabled

[brianp]

Description

Pool API requests were firing during wallet init even when the user had pools turned off. The handle_wallet_address_change calls on both CpuPoolManager and GpuPoolManager ran unconditionally, hitting the pool API over HTTP every time the wallet initialized.

Now we check cpu_pool_enabled / gpu_pool_enabled before calling those handlers.

Motivation and Context

Unnecessary HTTP requests to pool APIs when pools are off. Wasted bandwidth and log noise for solo miners.

Closes #3165

How Has This Been Tested?

• Disabled pool mining, restarted app, confirmed no Requesting ... pool status from: log lines during wallet init
• Enabled pool mining, confirmed pool status requests still fire normally

What process can a PR reviewer use to test or verify this change?

1. Set cpu_pool_enabled and gpu_pool_enabled to false in pool config
2. Start the app and watch logs for pool status request lines
3. They shouldn't appear during wallet initialization
4. Toggle pools back on, restart, confirm they show up again

Breaking Changes

• None
• Requires data directory on base node to be deleted
• Requires hard fork
• Other - Please specify

[gemini-code-assist]

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