feat: pruning migration

[EgeCaner]

Adds optional migration for history-pruning (migration/historyprunner) that brings an existing node's database in line with the rolling pruner's retention window. Activated whenever --prune-mode is passed (with or without a value, including --prune-mode=0); no-op otherwise.

The migration runs in two pipelined, resumable phases. The keeper window is anchored on the L1-verified head (matching the rolling pruner's reorg-safe floor): with minHead = min(l1Head, chainHeight) and retainedBlocks taken from the --prune-mode=N value (defaulting to 0 when the flag is passed bare), the window covers [minHead - retainedBlocks + 1, chainHeight]. If minHead < retainedBlocks the chain is shorter than the window and the migration no-ops, leaving the rolling pruner to take over once blocks arrive.

• Stager — range-deletes the cold number-keyed buckets and wipes reverse-lookup buckets (TransactionBlockNumbersAndIndicesByHash, L1HandlerTxnHashByMsgHash, BlockHeaderNumbersByHash), then copies in-window entries from the live history buckets (ContractStorageHistory, ContractClassHashHistory, ContractNonceHistory) into a scratch namespace.
• Restorer — wipes the live history buckets, copies keepers back from scratch, and rebuilds the reverse-lookup indices per block. Wipes the scratch namespace on completion.

Resume state (stagerProgress | restorerProgress | numRetainedBlocks, 24 bytes BE) is persisted between runs; the originally-configured retention pins the cutoff so a --prune-mode change mid-flight cannot retarget an in-progress migration (logged when ignored).

[codecov]

Codecov Report

❌ Patch coverage is 73.67150% with 109 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.87%. Comparing base (af1fe00) to head (b45d05e).

Files with missing lines	Patch %	Lines
migration/historyprunner/migrator.go	72.46%	32 Missing and 25 partials ⚠️
migration/historyprunner/restorer.go	61.01%	16 Missing and 7 partials ⚠️
migration/historyprunner/copy.go	67.50%	8 Missing and 5 partials ⚠️
migration/historyprunner/stager.go	78.12%	4 Missing and 3 partials ⚠️
node/migration.go	0.00%	6 Missing ⚠️
migration/historyprunner/committer.go	89.47%	1 Missing and 1 partial ⚠️
migration/progresslogger/block_progress_tracker.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #3597    +/-   ##
========================================
  Coverage   75.87%   75.87%            
========================================
  Files         387      393     +6     
  Lines       34918    35330   +412     
========================================
+ Hits        26493    26806   +313     
- Misses       6556     6614    +58     
- Partials     1869     1910    +41     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.