feat(zones): rename tabs to zones across api, ui, and storage

Made-with: Cursor

docs/SPECIFICATION.md

@@ -351,9 +351,9 @@ Manage connected devices and create/manage device groups.
 #### Layout
 - **Header:** Title with "Add Device" button
 - **Tabs:** Devices and Groups tabs
-- **Content Area:** Tab-specific content
+- **Content Area:** Zone-specific content
 
-#### Devices Tab
+#### Devices Zone
 
 **Device List**
 - **Display:** List of all known devices
@@ -375,7 +375,7 @@ Manage connected devices and create/manage device groups.
 - **Actions:** Cancel, Save
 - **Note:** Only one master device per system. Adding a new master will demote existing master to slave.
 
-#### Groups Tab
+#### Groups Zone
 
 **Group List**
 - **Display:** List of all device groups
@@ -397,7 +397,7 @@ Manage connected devices and create/manage device groups.
 - **Actions:** Cancel, Create
 
 #### Design Specifications
-- **Tab Style:** Active tab has purple background, white text
+- **Zone Style:** Active zone has purple background, white text
 - **List Items:** Bordered cards with hover effects
 - **Modal:** Centered overlay with white card, shadow
 - **Status Badges:** Colored pills (green for online, red for offline)
@@ -1495,7 +1495,7 @@ peak_mem = usqlite.mem_peak()
 
 ### Flow 2: Create Device Group
 
-1. User navigates to Device Management → Groups tab
+1. User navigates to Device Management → Groups zone
 2. User clicks "Create Group", enters name, selects pattern/settings
 3. User selects devices to add (can include master), clicks "Create"
 4. Group appears in list