rebrand: sweep remaining switchboard refs + rename cookies/storage keys

- CSS headers (4 files): Switchboard Core → Armature
- Editor .mjs headers (8 files): Chat Switchboard → Armature
- SQL migration comments + seed data (20 files): Switchboard Core → Armature
- Webhook header: X-Switchboard-Event → X-Armature-Event
- Cookie: sb_token → arm_token (3 Go files + auth.js)
- localStorage: sb_auth → arm_auth (auth.js + 2 test runners)
- localStorage: switchboard_theme → armature_theme (theme.js + base.html)
- Debug engine filter: chatSwitchboard/switchboard/sb_ → armatureChat/armature/arm_
- JS export: switchboardTheme → armatureTheme (theme.mjs + code-editor.mjs)

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

server/handlers/auth.go

@@ -153,8 +153,8 @@ func (h *AuthHandler) Logout(c *gin.Context) {
 		h.uekCache.Evict(userID.(string))
 	}
 
-	// Clear the sb_token cookie so SSR middleware doesn't trust a stale token
-	c.SetCookie("sb_token", "", -1, "/", "", false, false)
+	// Clear the arm_token cookie so SSR middleware doesn't trust a stale token
+	c.SetCookie("arm_token", "", -1, "/", "", false, false)
 
 	c.JSON(http.StatusOK, gin.H{"message": "logged out"})
 }
@@ -287,7 +287,7 @@ func (h *AuthHandler) OIDCCallback(c *gin.Context) {
 	userJSON, _ := json.Marshal(tokens["user"])
 
 	// Set page-auth cookie too (for SSR middleware)
-	c.SetCookie("sb_token", accessToken, 900, "/", "", false, false)
+	c.SetCookie("arm_token", accessToken, 900, "/", "", false, false)
 
 	// Base64-encode the token payload for the fragment
 	payload := fmt.Sprintf(`{"access_token":"%s","refresh_token":"%s","user":%s}`,