perf(model): one Joern invocation per query kind, not one per region

JVM startup dominated a scan: a call per region per family put a ten-line
file at 275s over three regions, and would have put a thousand regions at
roughly fifty hours. The queries themselves are milliseconds once the CPG
is loaded, so the cost was almost entirely process starts.

scan_repository() is now collect -> batch -> arbitrate. The three .sc
scripts accept a `requests` JSON map and answer all of them in one run,
keeping the single-request form so the committed measurements stay
reproducible byte-for-byte. Arbiters are untouched: each is handed a
CpgResult whose `run` returns its own prefetched rows.

The batcher builds parameters by calling request_params() extracted from
taint.py, dominance.py and config_value.py rather than reconstructing
them. A second copy that drifts from the arbiter's is the exact shape of
the five family-assumption bugs the predecessor spec spent a session
finding; there is now one definition per family and the batcher borrows
it.

Regions are also deduplicated by (path, function), collapsing the
nameless entry-point rows that were producing `model:injection:?:10`.

Measured on the same ten-line file: 275s -> 106s, three duplicate
findings -> one `model:injection:ping:10`, rung unchanged at
model_entailed. Gates byte-identical.

Server mode is recorded as task 2.3, deliberately sequenced after the
repository measurement: whether the remaining ~100s floor is worth a
process model, a weakened subprocess seam and a Scala-evaluating HTTP
endpoint depends on a build-time-to-query-time ratio only 2.2 produces.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

src/openultrasast/model/dominance.py

@@ -26,12 +26,14 @@ from .ladder import Rung, Verdict
 from .specs import DominanceSpec
 
 
+def request_params(spec: DominanceSpec, *, function: str = "") -> dict[str, object]:
+    """The query parameters this arbiter sends. Shared with the batcher; see the note in `taint.request_params`."""
+    return {"operations": spec.operations, "dischargers": spec.dischargers, "function": function}
+
+
 def verdict(cpg: CpgResult, spec: DominanceSpec, *, function: str = "") -> Verdict | None:
     """The verdict for the obligated operation in ``function``, or ``None`` when there is nothing to say."""
-    rows = cpg.run(
-        "dominance",
-        {"operations": spec.operations, "dischargers": spec.dischargers, "function": function},
-    )
+    rows = cpg.run("dominance", request_params(spec, function=function))
     operations = _operations(rows)
     if not operations:
         return None
@@ -85,4 +87,4 @@ def _operations(rows: object) -> list[dict[str, object]]:
     return kept
 
 
-__all__ = ["verdict"]
+__all__ = ["request_params", "verdict"]