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/app/app.go

@@ -13,6 +13,7 @@ import (
 	"github.com/andydixon/noema/internal/audit"
 	"github.com/andydixon/noema/internal/auth"
 	"github.com/andydixon/noema/internal/config"
+	"github.com/andydixon/noema/internal/minds"
 	"github.com/andydixon/noema/internal/observability"
 )
 
@@ -24,6 +25,7 @@ type Deps struct {
 	Auth       *auth.Service
 	Audit      *audit.Logger
 	Metrics    *observability.Metrics
+	Minds      *minds.Store
 	Migrations fs.FS
 	Started    time.Time
 }