perf(trie): feature gate reth-optimism-trie metrics

[emhane]

Closes #281

• Feature gates reth-optimism-trie metrics
• Moves cursor impls out of proofs module into new module cursor
• Moves cursor factory impls into new module cursor_factory
• Updates cursor factory impls to return cursor types with metrics wrapper if metrics feature is enabled

[Copilot]

Pull Request Overview

This PR feature gates the reth-optimism-trie metrics functionality to reduce overhead when metrics are not needed, while also refactoring cursor implementations into dedicated modules for better organization.

Key changes:

• Adds metrics feature flag for optional metrics collection
• Extracts cursor implementations into new cursor and cursor_factory modules
• Renames core traits (OpProofsStorage → OpProofsStore, OpProofsTrieCursor → OpProofsTrieCursorRO, etc.)

Reviewed Changes

Copilot reviewed 16 out of 18 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
crates/optimism/trie/Cargo.toml	Adds metrics feature flag
crates/optimism/trie/src/api.rs	Renames traits and adds From conversion for OpProofsStorageError
crates/optimism/trie/src/lib.rs	Exports types conditionally based on metrics feature
crates/optimism/trie/src/cursor.rs	New module containing cursor wrapper implementations
crates/optimism/trie/src/cursor_factory.rs	New module containing cursor factory implementations
crates/optimism/trie/src/metrics.rs	Updates to use renamed traits and add type aliases
crates/optimism/trie/src/proof.rs	Removes cursor implementations (moved to cursor module)
crates/optimism/trie/src/provider.rs	Uses Constructor derive and updated storage type
crates/optimism/trie/src/live.rs	Uses Constructor derive and updated storage type
crates/optimism/trie/src/in_memory.rs	Updates trait implementations to use renamed traits
crates/optimism/trie/src/db/store.rs	Updates trait implementation to use renamed trait
crates/optimism/trie/src/db/cursor.rs	Updates trait implementations to use renamed traits
crates/optimism/trie/src/backfill.rs	Updates trait bounds to use renamed trait
crates/optimism/trie/tests/lib.rs	Updates type references to use renamed types
crates/optimism/rpc/src/eth/proofs.rs	Updates type references and trait bounds
crates/optimism/exex/src/lib.rs	Updates trait bounds to use renamed trait

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

The documentation comment incorrectly refers to OpProofsStorageWithMetrics. Since this is a feature-gated alias that conditionally wraps storage based on the metrics feature, the comment should clarify that this is a metrics-enabled wrapper of OpProofsStore, not just reference the struct name. Consider: /// Metrics-enabled wrapper for [OpProofsStore].

Suggested change

	/// Alias for [`OpProofsStorageWithMetrics`].
	/// Metrics-enabled wrapper for [`OpProofsStore`].

[Copilot]

The documentation comment should not include implementation details about feature flags. The comment should describe what the type represents from the user's perspective, regardless of feature flags. Consider: /// Alias for [OpProofsStore] without metrics collection.

Suggested change

	/// Alias for [`OpProofsStore`] type without metrics (`metrics` feature is disabled).
	/// Alias for [`OpProofsStore`] without metrics collection.

[emhane]

added inline attributes so that benchmarks wouldn't be effected by these function calls from wrapping types at least when not built with maxperf

[meyer9]

nice clean up!

[emhane]

merging so that this new fs structure can be used as base for new prs. will fix lint tomorrow.