no-em-dash pre-commit hook for user-facing strings, existing em-dashes rewritten

frontend/scripts/no-em-dash.ts walks src/ with the TypeScript parser and flags
an em-dash in JSX text, string literals and template text. A bare "—"
placeholder passes, separators go in no-em-dash.allow.json. The script is
identical to index's copy.

frontend/src/components/Runs/RunsScreen.tsx

@@ -255,7 +255,7 @@ export function RunsScreen({
           names={selected.map(shortId)}
           noun="run"
           pending={remove.isPending}
-          description="A run still going is cancelled first. What it recorded — its numbers, its nodes and the outputs other runs reuse from the cache — goes with it, and nothing brings it back."
+          description="A run still going is cancelled first. Its numbers, its nodes and the outputs other runs reuse from the cache go with it, and nothing brings them back."
           onConfirm={() => remove.mutate(selected)}
         />
 
@@ -288,10 +288,10 @@ export function RunsScreen({
             {runs.length} run{runs.length === 1 ? "" : "s"}
             {selected.length > 0 ? `, ${selected.length} picked` : ""}
             {selected.length >= MAX_SELECTION
-              ? ` — ${MAX_SELECTION} is as many as one comparison carries`
+              ? `. ${MAX_SELECTION} is as many as one comparison carries`
               : ""}
             {!hasNextPage && runs.length >= LIST_CAP
-              ? ` — the newest ${LIST_CAP}, which is as deep as this list reads`
+              ? `. The newest ${LIST_CAP} is as deep as this list reads`
               : ""}
           </p>
         </div>

frontend/src/components/Runs/queries.ts

@@ -283,7 +283,7 @@ export async function cancelThenDelete(runId: string) {
  * left as an empty chart, which reads as a fault.
  */
 export const NO_CURVE =
-  "No curve was recorded. A node restored from the cache is read back from the run that produced it, so this draws nothing once that run has been deleted — its outputs are still on the result."
+  "No curve was recorded. A node restored from the cache is read back from the run that produced it, so this draws nothing once that run has been deleted. Its outputs are still on the result."
 
 /**
  * Which restored nodes lost their curve, and with which deleted run.