Add entity-aware fact resolution against Nexus (Vikunja #279)

facts gain a Subject/EntityID/ResolutionState triple and an async
enrichment worker that resolves free-text subjects to canonical Nexus
entity_ids, mirroring Praxis's enrichment-worker pattern. Ambiguous or
unreachable Nexus never guesses an entity_id — the fact stays pending
or terminal-ambiguous instead.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018ghELqYhZNLub2TXGMazqA

cmd/mavend/main.go

@@ -249,6 +249,7 @@ func run(args []string) error {
 		tl          *tickLoop
 		coreAPI     ipc.CoreAPI
 		eco         *ecosystemWiring
+		factWorker  *factEnrichmentWorker
 	)
 
 	if !locked {
@@ -341,6 +342,7 @@ func run(args []string) error {
 		repeatInterval := time.Duration(cfg.RepeatInterval)
 		autotuneInterval := time.Duration(cfg.AutotuneInterval)
 		tl = newTickLoop(st, gatherer, dispatcher, phr, rules, tickInterval, repeatInterval, autotuneInterval, cfg.Digest, routinesFromConfig(cfg.Routines))
+		factWorker = newFactEnrichmentWorker(st, eco, time.Duration(cfg.FactEnrichmentInterval))
 
 		coreAPI = &daemonAPI{
 			CoreAPI:  ipc.NewStoreAPI(st),
@@ -500,6 +502,7 @@ func run(args []string) error {
 			repeatInterval := time.Duration(cfg.RepeatInterval)
 			autotuneInterval := time.Duration(cfg.AutotuneInterval)
 			tl = newTickLoop(st, gatherer, dispatcher, phr, rules, tickInterval, repeatInterval, autotuneInterval, cfg.Digest, routinesFromConfig(cfg.Routines))
+			factWorker = newFactEnrichmentWorker(st, eco, time.Duration(cfg.FactEnrichmentInterval))
 
 			// Swap the CoreAPI from lockedAPI to the real store adapter.
 			newAPI := &daemonAPI{
@@ -530,6 +533,11 @@ func run(args []string) error {
 				tl.run(ctx)
 			}()
 
+			// Start fact-entity enrichment worker.
+			go func() {
+				factWorker.run(ctx)
+			}()
+
 			dl.unlock()
 			log.Printf("mavend: unlocked via passkey assertion")
 			return nil
@@ -563,6 +571,11 @@ func run(args []string) error {
 			defer wg.Done()
 			tl.run(ctx)
 		}()
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			factWorker.run(ctx)
+		}()
 	}
 
 	<-ctx.Done()