Add Canary wallet monitoring app

[schjonhaug]

Description

Adds Canary - a Bitcoin wallet monitoring and early warning system for cold storage.

Features:

• Watch-only wallet monitoring via output descriptors
• Instant notifications via ntfy push notifications
• Transaction detection with RBF/CPFP awareness
• Balance alerts (threshold-based notifications)
• Deep wallet scanning for comprehensive history
• Multi-language support

Canary connects to the local Electrum server (electrs) to monitor wallets without requiring private keys.

Checklist

• tested successfully on local MyNode, if yes, list the device(s) below

List of test device(s)

• PC (MyNode)

[schjonhaug]

@tehelsper , do you have any time soon to take a look at this?

[tehelsper]

I should be able to get to it in the next release. I've got a couple quick comments. Thanks!

• Can you update to v1.4.0? Looks like you have a new release out.
• Can you update the install script to use the VERSION for the version? Apps like albyhub might be a good example.

[schjonhaug]

I can update this to v1.4.0, but I’d prefer not to do that yet without testing it on a real myNode device first. v1.4.0 adds new self-hosted behavior around local Mempool integration, and I haven’t had a chance to validate that path on actual myNode hardware yet. ntfy should be fine since it’s configured in Canary’s settings and defaults to ntfy.sh, but local Mempool support on myNode likely deserves a proper follow-up so Canary can detect and use the local instance cleanly.

Since I have tested the integration itself on a real myNode box with the current Canary build, I think the safer path for this PR is to keep it on the tested version for now, and then do a follow-up bump to v1.4.0 once I can verify the myNode-specific Mempool behavior properly.