feat: skip deposit already created in the session

[matteojug-stacks]

Keep track of deposits created in the current run and skip creating them multiple times.

Also:

• bump rust to latest
• update the "default" config

Testing Information

Tested locally with #17

[Copilot]

Pull request overview

This PR reduces redundant calls to Emily by tracking deposits created during the current process run and skipping re-creation attempts for the same (txid, vout) pair. It also updates the default configuration and bumps the Rust toolchain version.

Changes:

• Track locally created deposits in DepositMonitor via an LRU cache and skip them when building pending deposit requests.
• Record successful deposit creation events from the main runloop into the monitor.
• Update default.toml lock time and bump the Rust toolchain version.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/main.rs	Records successful deposit creation in the monitor to enable session-level deduping.
src/deposit_monitor.rs	Adds an LRU cache for created deposits and filters out already-created UTXOs from pending deposit generation.
src/config/default.toml	Updates default lock_time and clarifies reclaim script configuration guidance.
rust-toolchain.toml	Bumps Rust toolchain channel to a newer version.
Cargo.toml	Normalizes dependency formatting (no functional change).

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[djordon-stacks]

Largely looks good, just one small nit.