feat: optimised initial state update for pruning

[dhyaniarun1993]

Closes #562

Validated the optimization by rewriting an initial state with N=50,000 updated entries.

• Throughput: Increased by ~20.9% (326k → 394k entries/sec).
• Latency: Reduced by ~17.2% (153ms → 126ms).

Old approach:
Rewrite Duration: 153.26ms
Throughput:       326,248 entries/sec

New approach:
Rewrite Duration: 126.77ms
Throughput:       394,410 entries/sec

bench: 180e132

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 38.45%. Comparing base (e21a30b) to head (3c59600).

Additional details and impacted files

Files with missing lines	Coverage Δ
crates/optimism/trie/src/db/store.rs	98.17% <100.00%> (-0.04%)	⬇️
crates/optimism/trie/src/prune/pruner.rs	95.18% <100.00%> (ø)

... and 19 files with indirect coverage changes

Flag	Coverage Δ
e2e	35.86% <92.30%> (+0.21%)	⬆️
unit	26.89% <92.30%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
reth binary	53.14% <ø> (ø)
op historical proof	89.93% <100.00%> (-0.02%)	⬇️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Copilot]

Pull request overview

This PR optimizes the initial state update operation during pruning, achieving approximately 20.9% throughput improvement and 17.2% latency reduction. The optimization restructures the database write strategy from an interleaved approach to a more efficient two-phase sequential approach.

Key changes:

• Restructured prune mode database operations to use sequential batch deletion followed by batch writes instead of interleaved operations
• Corrected timing measurement to include all fetch operations (trie updates and block hashes) in the reported fetch duration

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
crates/optimism/trie/src/prune/pruner.rs	Moved fetch_duration measurement to after block hash fetches for accurate timing attribution
crates/optimism/trie/src/db/store.rs	Refactored persist_history_batch prune mode logic to use two-phase approach: batch delete all block 0 entries, then batch write non-tombstones

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[emhane]

lgtm

[emhane]

nice

[emhane]

thank you for the numbered steps in these code comments, improves readability