Add pedigree lookup and ancestry tree page

New 🌳 Pedigree view: enter a dog's ISO chip or SKK registration number
and see its ancestry rendered as a tree. SKK has no public API, so the
server drives SKK Hunddata like a browser: it resolves the input to an
internal hundid via the Hund_sok.aspx/HundData page-method, renders 7
generations per pedigree page, parses the rowspan grid into ahnentafel
positions, and follows each generation's leaves deeper by reading their
hundid out of the __doPostBack response viewstate.

A lookup returns the first 7 generations immediately and crawls deeper in
the background; the client polls and fills the tree in as ancestors
arrive. Finished trees are cached per dog in a new pedigree_cache table
(pedigrees don't change), so a dog is crawled once and repeats are instant.
The endpoints sit behind auth like the rest of /api/*, and the crawl is
kept polite (warmed session, delay between requests, one coalesced job per
dog, hard caps).

server/main.go

@@ -311,6 +311,13 @@ func openDB(path string) (*sql.DB, error) {
 			user_id TEXT NOT NULL,
 			created INTEGER NOT NULL,
 			expires INTEGER NOT NULL
+		);
+		CREATE TABLE IF NOT EXISTS pedigree_cache (
+			hundid      TEXT PRIMARY KEY,
+			subject     TEXT NOT NULL DEFAULT '',
+			nodes       TEXT NOT NULL DEFAULT '',
+			generations INTEGER NOT NULL DEFAULT 0,
+			fetched     INTEGER NOT NULL DEFAULT 0
 		);`
 	if _, err := db.Exec(schema); err != nil {
 		db.Close()
@@ -600,6 +607,7 @@ func main() {
 	store := newStore(db)
 	configStore := newConfigStore(db)
 	exerciseStore := newExerciseStore(db)
+	pedigrees := newPedManager(db)
 
 	photosDir := filepath.Join(filepath.Dir(*dataPath), "photos")
 	if err := os.MkdirAll(photosDir, 0o755); err != nil {
@@ -711,6 +719,24 @@ func main() {
 		}
 	}))
 
+	// POST /api/pedigree — resolve a dog by chip / registration number / name and
+	// return its ancestry tree (immediately for the first generations, then a
+	// background crawl deepens it). GET /api/pedigree/status polls that crawl.
+	mux.HandleFunc("/api/pedigree", auth.requireUser(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		pedigrees.handleLookup(w, r)
+	}))
+	mux.HandleFunc("/api/pedigree/status", auth.requireUser(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		pedigrees.handleStatus(w, r)
+	}))
+
 	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte("ok"))
 	})