feat(settings): lead with version + update, tail the rest of System

App Settings opened on a System section that mixed the two things worth seeing
immediately (what this install runs, whether a newer release is waiting) with
three groups nobody sets twice (CLAUDE.md template path, default working
directory, image watcher, Cloudflare tunnel).

Split in two. **Updates** is now the first section and carries only the current
version and the update action, so the modal opens on it and the second thing in
reach is Terminal & Input, where Local Echo lives. **System** keeps Paths,
Automation and Remote access and tails the document, last in the rail.

Also fixes the admin-ui load-order test, which broke on this branch: it located
the modules with a bare `indexOf('session-ui.js')`, and the modal markup now
cites those modules in comments well above the script tags, so it was comparing
a comment against a `<script src>`. It matches the script tag itself now.

docs/architecture-invariants.md

@@ -234,7 +234,7 @@ Anatomy: `.set-shell` → `.set-shell-head` (title + `.set-head-actions`) + `.se
 
 **The rail means two different things, and that is deliberate:**
 
-- **App Settings** is a **table of contents over ONE scrolling document**. Every section stays mounted; rail entries carry `data-section` and `switchSettingsTab(id)` keeps its historical name but SCROLLS instead of hiding. Section order in the DOM is `settings-system|terminal|layout|appearance|models|clis|notifications|voice|shortcuts`, and the modal opens scrolled to **System**: the version this install runs and whether an update is waiting are the first thing you see, with Updates promoted above Paths/Automation/Remote access.
+- **App Settings** is a **table of contents over ONE scrolling document**. Every section stays mounted; rail entries carry `data-section` and `switchSettingsTab(id)` keeps its historical name but SCROLLS instead of hiding. Section order in the DOM is `settings-updates|terminal|layout|appearance|models|clis|notifications|voice|shortcuts|system`, and the modal opens scrolled to **Updates**, which carries ONLY the current version and the update action: what this install runs, and whether a newer release is waiting, before any preference. The rest of the old System section (Paths, Automation, Remote access) tails the document under **System**, set once and rarely touched, which puts Terminal & Input (where Local Echo lives) second in reach.
 - **Session Options** and **Add Case** really SWITCH: `switchOptionsTab(tab)` / `switchCaseModalTab(tab)` (session-ui.js) show one `.set-section` and put `.hidden` on the rest, then reset the document scroll so a switched-to section starts at its own top. Stacking them into one document would bury both ends: Summary owns its own scroller, Respawn is long, and Add Case is six independent forms. Their rail entries call the handler from an inline `onclick` and pair by id (`data-tab="respawn"` ↔ `#respawn-tab`; `data-tab="case-clone"` ↔ `#case-clone`).
 
 ⚠️ **The Session Options rail reads "Session" but the key is still `context`.** The tab was renamed because "context" described only one of its three groups (they are now Identity / Context window / Behavior), and the rename is **label-only**: `data-tab="context"`, `id="context-tab"` and `switchOptionsTab('context')` are unchanged, including the call in `openSessionOptions` that lands external-CLI sessions somewhere valid.