Add comprehensive documentation for various app features

- Introduced "Contacts" documentation detailing the contact management system, types, list, search, and tap actions.
- Added "Map & Location" documentation covering map features, interactions, path tracing, and line-of-sight analysis.
- Created "Navigation" documentation outlining app flow, QuickSwitchBar, and device screen interactions.
- Developed "Notifications" documentation explaining notification types, in-app badges, settings, and rate limiting.
- Established "Repeater Management" documentation for managing repeaters and room servers, including CLI access and telemetry.
- Compiled "Scanner & Connection" documentation detailing BLE, USB, and TCP connection processes.
- Formulated "Settings" documentation outlining access, layout, device info, app settings, node settings, actions, debug options, export features, and about section.

documentation/notifications.md

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+# Notifications
+
+## Overview
+
+MeshCore Open provides both **system notifications** (push-style OS alerts) and **in-app unread badges** to inform users of new activity.
+
+## Notification Types
+
+### 1. Direct Message Notifications
+- **Triggered when**: A new incoming message arrives from a Chat or Room contact
+- **Title**: Contact's name
+- **Body**: Message text (reactions show "Reacted [emoji]", GIFs show "Sent a GIF")
+- **Priority**: High
+- **Android channel**: `messages`
+
+### 2. Channel Message Notifications
+- **Triggered when**: A new message arrives on a non-muted channel
+- **Title**: Channel name (or "Channel N" if unnamed)
+- **Body**: `"<senderName>: <message text>"`
+- **Priority**: High
+- **Android channel**: `channel_messages`
+
+### 3. Advertisement Notifications
+- **Triggered when**: A new node is discovered on the mesh for the first time
+- **Title**: "New [type] discovered" (e.g., "New chat node discovered")
+- **Body**: Contact's name
+- **Priority**: Default
+- **Android channel**: `adverts`
+
+### 4. Background Service Notification (Android Only)
+- A persistent low-priority notification: "MeshCore running — Keeping BLE connected"
+- Required by Android for foreground services to keep BLE alive in the background
+- Tap to re-launch the app
+- **Does not auto-start on reboot** — the user must re-open the app manually after a phone restart
+
+### Notification Tap Behavior
+
+Tapping a notification currently re-launches the app at the root route. It does **not** navigate directly to the relevant chat or channel.
+
+## In-App Unread Badges
+
+Red numeric badges appear throughout the UI:
+- **Contacts list**: Each contact row shows a red pill badge (e.g., "3") for unread messages
+- **Channels list**: Each channel row shows an unread badge
+- **Chat screen subtitle**: Shows unread count inline
+- Badges cap at "99+" for display
+
+### How Unread Counts Work
+
+- Stored per contact (by public key) and per channel, **scoped to the connected device's identity** (first 10 hex characters of its public key). Switching between different radios gives each its own independent unread state
+- **Suppressed when viewing**: Opening a chat resets the count to 0 and cancels the OS notification
+- **Ignored for**: Outgoing messages, CLI messages, and repeater contacts
+- Debounced writes (500ms) to avoid excessive storage I/O during message bursts
+
+## Notification Settings
+
+Access via **App Settings → Notifications**:
+
+| Setting | Default | Description |
+|---|---|---|
+| Enable Notifications | On | Master toggle; requests OS permission when turned on |
+| Message Notifications | On | DM alerts (greyed out if master is off) |
+| Channel Message Notifications | On | Channel alerts (greyed out if master is off) |
+| Advertisement Notifications | On | New node alerts (greyed out if master is off) |
+
+### Per-Channel Muting
+
+Long-press a channel in the channels list → "Mute channel" / "Unmute channel". Muted channels do not generate OS notifications.
+
+There is no per-contact muting.
+
+## Rate Limiting
+
+The notification system prevents notification storms:
+- **Minimum interval**: 3 seconds between individual notifications
+- **Batch window**: If multiple notifications arrive within 5 seconds, they are combined into a single summary notification on a fourth Android channel (`batch_summary`): "MeshCore Activity — 2 messages, 1 channel message, 3 new nodes". Note: batch summaries are Android-only; on Apple platforms individual notifications are shown
+
+## Notification Clearing
+
+- **Opening a contact chat**: Cancels the OS notification and resets unread count
+- **Opening a channel**: Cancels the channel notification and resets unread count
+- **Opening Contacts screen**: Cancels all advertisement notifications
+
+## Platform Support
+
+| Platform | Message Notifs | Badge | Background Service |
+|---|---|---|---|
+| Android | Yes | Via notification number | Yes (foreground service) |
+| iOS | Yes | Yes (app badge) | No |
+| macOS | Yes | Yes | No |
+| Windows | Yes | No | No |
+| Linux | Yes (if D-Bus available) | No | No |