refactor: low-regret cleanup across core, engine, dashboard

- core: extract ai-engine-loader.ts to share @fusion/engine dynamic-import
  boilerplate between ai-summarize and memory-compaction (incl. AgentMessage
  type); collapse getInbox/getOutbox, listInsights/countInsights,
  listRuns/countRuns, and three hasProjectDb* variants behind shared helpers.
- core: drop unused pluginLoaderLog export; tighten two `any` casts
  (db.walCheckpoint row, plugin-loader error.code).
- engine: extract resolveRoleFallback helper from buildSessionSkillContext/Sync;
  remove 22 stale `eslint-disable no-explicit-any` directives across
  project-engine, self-healing, triage, worktree-pool.
- dashboard: apply ESLint autofix (let→const, empty `interface extends`→type).

All three packages: typecheck clean, full test suites pass (14,414 tests),
builds clean. Net lint: -31 warnings. No public behavior changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/components/ChatView.tsx

@@ -89,7 +89,7 @@ function formatModelTag(provider?: string | null, modelId?: string | null): stri
 
   // Gemini models: "gemini-2.5-pro" -> "Gemini 2.5 Pro"
   if (normalizedModel.includes("gemini")) {
-    let formatted = modelId
+    const formatted = modelId
       .replace(/^gemini[- ]/i, "Gemini ")
       .replace(/pro[- ](\d+)[- ](\d+)/i, "Pro $1.$2")
       .replace(/pro[- ](\d+)/i, "Pro $1")
@@ -100,7 +100,7 @@ function formatModelTag(provider?: string | null, modelId?: string | null): stri
   }
 
   // Generic fallback: capitalize first letter, replace hyphens with spaces
-  let formatted = modelId
+  const formatted = modelId
     .replace(/-/g, " ")
     .replace(/^\w/, (c) => c.toUpperCase())
     .replace(/\s+/g, " ")