Fix clang-tidy CI break by restoring 2-arg Ledger constructor compatibility

[Copilot]

Build with clang-tidy failed on release/6.x backport code because src/host/test/ledger.cpp contains call sites of Ledger(ledger_dir, wf), while only the chunk-threshold constructor shape was available there. This PR restores source compatibility without changing existing explicit-threshold behavior.

• API compatibility shim in Ledger

  • Added a 2-argument overload:
    • Ledger(const fs::path&, ringbuffer::AbstractWriterFactory&)
  • The overload delegates to the existing constructor with max_chunk_threshold_size, preserving current semantics while unblocking legacy/backport call sites.

• Scope

  • Single-file, surgical change in src/host/ledger.h.
  • No behavior changes for existing call sites that already pass chunk_threshold.

Ledger(
  const fs::path& ledger_dir,
  ringbuffer::AbstractWriterFactory& writer_factory) :
  Ledger(
    ledger_dir,
    writer_factory,
    max_chunk_threshold_size)
{}

[achamayou]

@copilot fix the formatting on the one file you changed.

[Copilot]

@copilot fix the formatting on the one file you changed.

Addressed in 2d2d319: I applied clang-format-compliant formatting in src/host/ledger.h for the new 2-arg Ledger overload.