feat: add mind model with versioned personality, templates and self-model

Phase 2. Minds are rows with a slug, status (active/disabled/archived),
cognitive configuration and a pointer to the current personality version.
Personalities are structured (identity, values, traits, communication,
behaviour, free text) with a deterministic Brief() used by prompts and the
editor preview. Every change appends a personality_versions row protected
by the append-only trigger; restore copies an old version forward.
Templates carry reusable personalities; minds record their overrides so a
template can be re-applied without losing mind-specific edits. The
self-model starts with structural limitations the mind cannot drop
(no policy changes, no influence over shutdown, no cross-mind access).

API, UI (list, overview, editor with sliders/diff/history/import/export,
template editor) and noemactl mind/template commands. All mutations are
audited with field-level diffs.

internal/api/server.go

@@ -51,6 +51,8 @@ func (s *Server) routes() {
 	m.Handle("GET /api/v1/me/tokens", require(auth.RoleObserver, s.myTokens))
 	m.Handle("DELETE /api/v1/me/tokens/{id}", require(auth.RoleObserver, s.myTokenRevoke))
 
+	s.mindRoutes()
+
 	m.HandleFunc("/api/", func(w http.ResponseWriter, r *http.Request) {
 		writeError(w, r, http.StatusNotFound, "not_found", "no such endpoint")
 	})