feat: port 5 vulnerability detection heuristics from am-i.exposed

[satsfy]

Depends on #16 (it will be in draft mode until its merged)

Ports 5 privacy heuristics inspired by am-i-exposed.

New privacy heuristics in this PR:

• Dust attack — detects wallets receiving dust intended to poison future spends or reveal ownership
• Peel chain — detects repeated spend patterns where value is peeled off across a chain of transactions
• Deterministic links — detects transaction structures that create strong, guessable links between inputs and outputs
• Unnecessary input — detects transactions that include more inputs than needed, increasing linkability
• Toxic change — detects change outputs that are especially privacy-damaging to spend later

Reviewer Notes

Run integration tests with cargo test.