v0.2.0.0 Point-in-Time Asset Availability

This release adds ledgr's first point-in-time asset-availability workflow: dated membership and status facts, complete session clocks, dynamic member-plus-held universes, strict gap handling, stale-mark valuation, controlled incomplete outcomes, and an executable survivorship-bias article. It also hardens the core API with eager fill reads, corrected reversal-fee allocation, durable run locators, restored sweep-review lineage, and a mechanically split run coordinator. Compatibility: corrected availability timing and new schema and identity versions mean affected runs may have different pulses, fills, and hashes; rerun them before equivalence comparisons. Legacy retained artifacts remain inspectable under their recorded conventions. Windows and Ubuntu package checks, pkgdown, and the 85.9 percent coverage gate passed. Full details are in NEWS.md and the v0.2.0.0 release closeout.