feat(core): dry-run mode for reclassify, and a per-kind tally

Production is frozen and sits on schema 19, so the content_kind correction it
needs cannot be applied yet. `--dry-run` runs the real UPDATEs and rolls the
transaction back, so an operator can see exactly what a run would touch before
touching a database they cannot easily restore — the counts are measured, not
predicted.

`updated_by_kind` reports the SHAPE of the change ("consumable 17, staff 3"),
which is the thing worth sanity-checking: a different shape means the source
profile moved and the mapping needs regenerating.

Measured against a copy of prod-core.db: 20 rows would change (17 consumable,
3 staff), 1966 already correct, 0 unmatched, and the copy was verified unchanged
afterwards.

src/main.rs

@@ -57,20 +57,24 @@ async fn main() -> Result<()> {
         return Ok(());
     }
 
-    // `openfut-core reclassify <request.json>` — correct the content_kind of
-    // already-imported owned rows. A profile import is once-only, so a taxonomy
-    // fix cannot arrive by re-importing; the adapter supplies card_id -> kind
-    // because only it can map its own taxonomy. Idempotent.
+    // `openfut-core reclassify <request.json> [--dry-run]` — correct the
+    // content_kind of already-imported owned rows. A profile import is
+    // once-only, so a taxonomy fix cannot arrive by re-importing; the adapter
+    // supplies card_id -> kind because only it can map its own taxonomy.
+    // Idempotent. `--dry-run` runs the same statements and rolls back, so an
+    // operator can see what a production run would touch before it touches it.
     if std::env::args().nth(1).as_deref() == Some("reclassify") {
         let path = std::env::args()
             .nth(2)
-            .context("usage: openfut-core reclassify <request.json>")?;
+            .context("usage: openfut-core reclassify <request.json> [--dry-run]")?;
+        let dry_run = std::env::args().any(|a| a == "--dry-run");
         let pool = db::init_pool(&cfg.database_url, cfg.max_connections).await?;
         db::run_migrations(&pool).await?;
         let raw = std::fs::read_to_string(&path)
             .with_context(|| format!("read reclassify request {path}"))?;
-        let req: openfut_core::services::import::ReclassifyRequest =
+        let mut req: openfut_core::services::import::ReclassifyRequest =
             serde_json::from_str(&raw).context("parse reclassify request JSON")?;
+        req.dry_run |= dry_run;
         let outcome = openfut_core::services::import::reclassify_owned_content(&pool, &req).await?;
         println!("{}", serde_json::to_string_pretty(&outcome)?);
         return Ok(());