fix: derived-state determinism, error visibility, metrics naming, HTTP hardening

- rebuild: fold observations per fingerprint in a total order
  (hcl DESC, node_id DESC, id DESC) so two nodes with identical logs
  rebuild identical entries (was: arbitrary bare-column row, merge-order
  dependent)
- threads: CreateThreadCluster uses INSERT OR IGNORE + existing-id
  fallback — concurrent auto-threaders converge instead of hitting UNIQUE
- errors surfaced instead of swallowed: scanEntries returns rows.Err(),
  Stats() fails fast on query errors, AutoLinkThreadObservations /
  linkTemporalNeighbors / golden-thread linking propagate failures,
  AddThreadNote + LinkObservationToThread write under one tx,
  watch records session upsert failures
- gossip client: push checks HTTP status and reports errors (a broken
  push direction no longer looks like a silent success); gossip diff
  gets a 10s timeout so a dead peer cannot hang the CLI
- ingest: failed source sweeps (obsidian/browser/gitea) are logged,
  and -d's help text now states its file-only scope
- watch --quiet: fatal errors go to stderr instead of io.Discard
- main: cobra SilenceErrors/SilenceUsage (errors print once, usage is
  not dumped on runtime failures); knox mcp exits 0 on SIGINT/SIGTERM
- metrics: drop _total suffix from gauges (knox_observations,
  knox_entries, knox_projects, knox_sessions, knox_peers, knox_threads);
  _total stays on counters per Prometheus convention
- http: ReadHeaderTimeout + IdleTimeout on gossip, metrics, and web servers

tests: concurrent cluster-create idempotency, HCL-order rebuild fold
(both merge orders), push HTTP-error surfacing; full suite + -race pass,
gofmt clean

internal/watch/watch.go

@@ -98,7 +98,7 @@ func (w *Watcher) Start() error {
 	// seed is still ingesting. Vault/dirs are logged after the seed below.
 	gossipAddr := ListenAddr()
 	node := &Node{Kdb: w.knoxDB, Name: "knox", Addr: gossipAddr, Metrics: w.metrics}
-	srv := &http.Server{Addr: gossipAddr, Handler: node.Handler()}
+	srv := &http.Server{Addr: gossipAddr, Handler: node.Handler(), ReadHeaderTimeout: 10 * time.Second, IdleTimeout: 60 * time.Second}
 	go func() {
 		log.Printf("[knox] gossip listening on %s", gossipAddr)
 		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
@@ -108,7 +108,7 @@ func (w *Watcher) Start() error {
 
 	// Prometheus scraping on a dedicated port (KNOX_METRICS_ADDR).
 	metricsAddr := MetricsAddr()
-	metricsSrv := &http.Server{Addr: metricsAddr, Handler: node.Metrics.Handler()}
+	metricsSrv := &http.Server{Addr: metricsAddr, Handler: node.Metrics.Handler(), ReadHeaderTimeout: 10 * time.Second, IdleTimeout: 60 * time.Second}
 	go func() {
 		log.Printf("[knox] metrics listening on %s", metricsAddr)
 		if err := metricsSrv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
@@ -367,8 +367,9 @@ func (w *Watcher) recordResult(result *ingest.IngestResult, trigger string) {
 	if result.SourceID == "opencode-session" {
 		sessionID, _ := result.Provenance["session_id"].(string)
 		if sessionID != "" {
-			status := "active"
-			w.knoxDB.UpsertSession(sessionID, result.Project, result.Title, status)
+			if err := w.knoxDB.UpsertSession(sessionID, result.Project, result.Title, "active"); err != nil {
+				log.Printf("[knox] session upsert error: %v", err)
+			}
 		}
 	}
 }