Closes out track 2's ADR-0015 backlog.
* `--resume` CLI flag (L1a, ADR-0015 §7) opens the most-
recently-used project, tracked in <data-root>/last_project.
Mutually exclusive with a positional <project-path>; errors
cleanly to stderr (above the shell prompt) on missing file
or stale recorded path. last_project is rewritten on every
successful project open (startup, load, new, save as,
import).
* Persistent input history (I2-persist, ADR-0015 §12). On
project open, the in-memory navigable history is hydrated
from the tail of history.log (capped at the in-memory cap).
ProjectSwitched gains a `history_entries` payload field;
App::seed_history is the entry point. Pipes inside source
text round-trip via splitn(3); unknown escape sequences are
passed through literally.
* Migration framework scaffold (F3, ADR-0015 §9). New
persistence::migrations module with MigratorRegistry +
migrate_to_latest + ensure_project_yaml_migrated. Empty
in v1 (production registry has no migrators); the loader
runs through it on every project open and is exercised by
tests with a fake v1→v2 migrator. Writes
project.yaml.v<N>.bak before any migrator runs; verifies
each step bumps the version field.
Refreshes docs/requirements.md (A1 / I2 / F3 / E1 / L1a /
test baseline) and adds docs/handoff/20260508-handoff-3.md
covering both Iter 5 and Iter 6.
Total tests: 408 passing, 0 failing, 0 skipped (up from 345
at handoff-2). Clippy clean.
claude@clouddev1