chore: complete ManaCore → Mana rename (docs, go modules, plists, images)

Final cleanup of references missed in previous rename commits:

- Dockerfiles: PUBLIC_MANA_CORE_AUTH_URL → PUBLIC_MANA_AUTH_URL
- Go modules: github.com/manacore/* → github.com/mana/* (7 go.mod files)
- launchd plists: com.manacore.* → com.mana.* (14 files renamed + content)
- Image assets: *_Manacore_AI_Credits* → *_Mana_AI_Credits* (11 files)
- .env.example files: ManaCore brand strings → Mana
- .prettierignore: stale apps/manacore/* paths → apps/mana/*
- Markdown docs (CLAUDE.md, /docs/*): mana-core-auth → mana-auth, etc.

Excluded from rename: .claude/, devlog/, manascore/ (historical content),
client testimonials, blueprints, npm package refs (@mana-core/*).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/shared-icons/package.json

@@ -2,7 +2,7 @@
 	"name": "@mana/shared-icons",
 	"version": "1.0.0",
 	"private": true,
-	"description": "Phosphor Icons for all Manacore SvelteKit web apps",
+	"description": "Phosphor Icons for all Mana SvelteKit web apps",
 	"type": "module",
 	"svelte": "./src/index.ts",
 	"main": "./src/index.ts",

packages/shared-icons/src/index.ts

@@ -1,7 +1,7 @@
 /**
  * @mana/shared-icons
  *
- * Phosphor Icons for all Manacore SvelteKit web apps
+ * Phosphor Icons for all Mana SvelteKit web apps
  * https://phosphoricons.com
  *
  * Usage: