src/target_revenue/metrics.py: compute_metrics(manifest, entries, as_of)
is pure/deterministic like fold.py, reusing fold.py/conversion.py
unchanged. Returns facts/calculations/forecasts as three explicitly
separated blocks (TrustServicePRD TS-FR-5), covering the mandatory Q9
set plus the recommended velocity/forecast tier - forecasts are always
null rather than populated once a Phase has converted or velocity is
non-positive, so nothing disguises a projection as a fact.
Adds GET /phases/{id}/metrics (unauthenticated per FR-9/FR-10).
tests/test_metrics.py (6 tests) needs no Docker/Postgres and runs
under plain system Python. One new Docker-gated test in
test_ledger_hosting.py proves the hosted /metrics response exactly
matches compute_metrics() run offline against the same export.