feat: add storage interface with pruning methods

[meyer9]

Fixes #177

I added a few methods that should allow atomically pruning and reorging blocks. Each function should represent a single transaction. We can store trie nodes, reorg, prune in a single transaction now. I kept the bulk insert methods available for storing the current state.

[wiz-b4c72f16a4]

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[Copilot]

Pull Request Overview

This PR introduces a storage interface with pruning and reorganization methods to support external proof generation. The interface defines traits for cursor-based operations and atomic storage transactions.

• Adds comprehensive storage traits for external proof data management
• Implements cursor-based iteration for trie nodes and hashed entries
• Provides atomic methods for pruning, reorganization, and bulk operations

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

File	Description
crates/exex/external-proofs/src/storage.rs	New storage interface with traits for cursors and external storage operations
crates/exex/external-proofs/src/lib.rs	Adds storage module declaration
crates/exex/external-proofs/Cargo.toml	Adds required dependencies for the storage interface

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[Copilot]

Incomplete documentation comment. The comment ends with 'and' but doesn't specify what happens after deletion.

Suggested change

	/// Deletes all updates > `latest_common_block_number` and
	/// Deletes all updates greater than `latest_common_block_number` and replaces them by adding the provided `blocks_to_add`.

[dhyaniarun1993]

Can we use thiserror for easier error definition?

Suggested change

	pub enum ExternalStorageError {
	Other(eyre::Error),
	}
	#[derive(Debug, Error)]
	pub enum ExternalStorageError {
	#[error("Other error: {0}")]
	Other(eyre::Error),
	}

[emhane]

lgtm, smol comment. pending @dhyaniarun1993

[emhane]

pls add a todo comment that this is just a placeholder

[emhane]

Suggested change

	#![allow(dead_code, unreachable_pub)]
	#![expect(dead_code, unreachable_pub)]

use expect instead of allow