feat: add immutable cognitive event store, live streams and event explorer

Phase 3. Events are the append-only record of everything a mind does
(ADR-0002). pkg/events defines the closed type vocabulary, categories,
evidence references and the observation payload with explicit trust
levels. The store validates and appends inside the caller's transaction,
publishes to a bounded fan-out bus only after commit, queries by seq
cursor with type/category/source/salience/confidence/time/search
filters, and walks provenance: cause, parents, children, cited evidence,
derived events and correlation groups. Durable per-consumer cursors never
move backwards.

Server-Sent Events streams (per mind and global) subscribe before
replaying history after Last-Event-ID so nothing is missed, apply the
same filter vocabulary live, and heartbeat. Operators can inject
observations tagged with operator trust for demos and tests.

UI: live thought stream with filters and paging, forensic event page
with causal chain and evidence navigation, dashboard important events.
Personality and status changes now leave operator_action events in the
mind's own history. CLI: event inspect/list/tail, observe.

internal/ui/ui.go

@@ -15,10 +15,12 @@ import (
 	"strings"
 	"time"
 
+	"github.com/andydixon/noema/internal/api"
 	"github.com/andydixon/noema/internal/app"
 	"github.com/andydixon/noema/internal/auth"
 	"github.com/andydixon/noema/internal/minds"
 	"github.com/andydixon/noema/internal/version"
+	"github.com/andydixon/noema/pkg/ids"
 	"github.com/andydixon/noema/web"
 )
 
@@ -27,7 +29,8 @@ type UI struct {
 	deps    app.Deps
 	pages   map[string]*template.Template
 	static  fs.FS
-	statusF func(r *http.Request) any // system status provider injected by api
+	statusF func(r *http.Request) any                                  // system status provider injected by api
+	ctxF    func(r *http.Request, id ids.ID) (api.EventContext, error) // event forensic context, shared with api
 }
 
 // View is the data passed to every template.
@@ -48,7 +51,7 @@ const flashCookie = "noema_flash"
 
 // New parses templates. In development, when ./web exists on disk, templates
 // and static files are read from disk so edits show without a rebuild.
-func New(deps app.Deps, statusF func(r *http.Request) any) (*UI, error) {
+func New(deps app.Deps, statusF func(r *http.Request) any, ctxF func(r *http.Request, id ids.ID) (api.EventContext, error)) (*UI, error) {
 	tmplFS, staticFS := web.Templates(), web.Static()
 	if !deps.Config.Production() {
 		if st, err := os.Stat("web/templates"); err == nil && st.IsDir() {
@@ -56,7 +59,7 @@ func New(deps app.Deps, statusF func(r *http.Request) any) (*UI, error) {
 			deps.Log.Info("ui: serving templates and static files from ./web (development)")
 		}
 	}
-	u := &UI{deps: deps, static: staticFS, statusF: statusF}
+	u := &UI{deps: deps, static: staticFS, statusF: statusF, ctxF: ctxF}
 	if err := u.parse(tmplFS); err != nil {
 		return nil, err
 	}
@@ -74,6 +77,12 @@ func (u *UI) parse(fsys fs.FS) error {
 		"pct":       func(f float64) string { return fmt.Sprintf("%.0f%%", f*100) },
 		"conf":      func(f float64) string { return fmt.Sprintf("%.2f", f) },
 		"inc":       func(i int) int { return i + 1 },
+		"deref": func(f *float64) float64 {
+			if f == nil {
+				return 0
+			}
+			return *f
+		},
 		"title":     func(s string) string { s = strings.ReplaceAll(s, "_", " "); return strings.ToUpper(s[:1]) + s[1:] },
 		"valueKeys": func() []string { return minds.ValueKeys },
 		"traitKeys": func() []string { return minds.TraitKeys },
@@ -198,6 +207,7 @@ func (u *UI) Register(m *http.ServeMux) {
 	m.Handle("POST /admin/users/{id}", u.require(auth.RoleAdministrator, u.usersUpdate))
 
 	u.mindRoutes(m)
+	u.eventRoutes(m)
 
 	for _, p := range []struct{ path, title, note string }{
 		{"/approvals", "Approvals", "The approval centre arrives with the capability system."},