docs: document Services UI refactor in wiki

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Personal Internet Cell – Project Wiki.md

@@ -16,12 +16,13 @@ The goal is to give a person full ownership of their core internet services on t
 4. [Authentication](#authentication)
 5. [API Reference](#api-reference)
 6. [DDNS](#ddns)
-7. [Service Store](#service-store)
-8. [Cell-to-Cell Networking](#cell-to-cell-networking)
-9. [Extended Connectivity](#extended-connectivity)
-10. [Security Model](#security-model)
-11. [Testing](#testing)
-12. [Development](#development)
+7. [Services UI](#services-ui)
+8. [Service Store (Add-ons)](#service-store-add-ons)
+9. [Cell-to-Cell Networking](#cell-to-cell-networking)
+10. [Extended Connectivity](#extended-connectivity)
+11. [Security Model](#security-model)
+12. [Testing](#testing)
+13. [Development](#development)
 
 ---
 
@@ -247,7 +248,61 @@ Supported providers: `pic_ngo`, `cloudflare`, `duckdns`, `noip`, `freedns`.
 
 ---
 
-## Service Store
+## Services UI
+
+### Navigation
+
+The left-hand navigation contains a **Services** group (previously labelled "Store"). Both admin and peer users see this group. It has three collapsible sub-items: **Email**, **Calendar**, and **Files**.
+
+Legacy paths redirect to their new canonical locations:
+
+| Old path | New path |
+|---|---|
+| `/email` | `/services/email` |
+| `/calendar` | `/services/calendar` |
+| `/files` | `/services/files` |
+| `/store` | `/services` |
+
+### Services page (`/services`)
+
+The top of the page shows a **Built-in** section with three cards — Email, Calendar, and Files. Each card has a **Manage** link that navigates to the corresponding sub-page.
+
+Below the Built-in section, the optional add-on store lists third-party services that can be installed or removed (see [Service Store (Add-ons)](#service-store-add-ons)).
+
+### Service sub-pages — admin view
+
+Each sub-page at `/services/email`, `/services/calendar`, and `/services/files` shows:
+
+1. **Connection info** — hostnames, ports, and protocol details (e.g. IMAP/SMTP/Webmail, CalDAV/CardDAV, WebDAV/Filegator).
+2. **Service status** — current running state fetched from the API.
+3. **Users list** — accounts registered with that service.
+4. **Inline config form** — editable fields for that service's settings:
+   - Email: ports and mail domain.
+   - Calendar: port and data directory.
+   - Files: ports, data directory, and per-user quota.
+
+Config forms save automatically with an 800 ms debounce after the last change. Dirty state persists through navigation: if a user edits the form and navigates away before the debounce fires, clicking **Apply Now** on return still saves the pending changes.
+
+### Service sub-pages — peer view
+
+Peers access the same URLs without an admin gate. The peer view shows only:
+
+- Connection info (hostnames, ports, copy buttons).
+- Personal credentials for that service (email address, CalDAV username, or WebDAV username), fetched from `/api/peer/*`.
+
+The config form and users list are not shown to peers.
+
+### Settings page
+
+The Email, Calendar, and Files configuration forms have been removed from the Settings page. Settings now covers: Identity, DDNS, Network (DNS/DHCP/NTP), WireGuard, Routing & Firewall, Vault & Trust, and Backup & Restore.
+
+### API change
+
+`GET /api/config` now includes an `installed_services` field — a dict keyed by service ID — listing services currently installed on the cell.
+
+---
+
+## Service Store (Add-ons)
 
 `ServiceStoreManager` fetches a manifest index from `http://git.pic.ngo/roof/pic-services/raw/branch/main/index.json`. Each manifest declares:
 - Container image