docs(wiki): a page for the help center

What the ? in the navbar opens, what an overview and a guide contain, how the
search and the screen switcher work, where the pictures come from and what
happens on a screen that has no help yet. Linked from the sidebar, from the
features list and from In-App-Help, which documents the other thing and was
being confused with it.

wiki/Help-Center.md

@@ -0,0 +1,92 @@
+# Help Center
+
+The help center is TREK's built-in guide to the screen you are on. It answers "what is this?" and
+"how do I do that?" without leaving the app, with a picture of every step taken from TREK itself.
+
+It is not the same thing as [In-App Help](In-App-Help), which is this wiki, rendered inside TREK at
+`/help`. The help center is the `?` panel; it links into the wiki wherever the reference
+documentation continues.
+
+## Opening it
+
+Click the **?** in the navbar, next to the theme toggle. It is the only way in, on purpose: a
+keyboard shortcut would fire while you were typing a question mark into a note.
+
+The panel opens over the app, already on the screen you were looking at. **Escape** closes it, and
+the focus goes back to the `?`. If you opened a dialog while following a guide, Escape closes that
+first.
+
+The `?` is a desktop control. On a phone the app does not show it.
+
+## What is in it
+
+The panel has navigation on the left and the content on the right.
+
+### The screen you are on
+
+The overview of a screen opens first. It carries:
+
+- the screen's **name and summary**, with a breadcrumb that says where it sits,
+- **Go to <screen>**, which closes the panel and takes you there,
+- a **full-frame picture** of the screen as you find it,
+- **On this screen**, a numbered list of what the screen holds and what each part does,
+- **How do I…**, a card per guide,
+- **In the docs**, the wiki pages that go deeper.
+
+A screen that has sub-screens lists them under **Sub-screens**, folded: the trip folds its plan
+columns, its panels and its tabs; Settings and the Admin panel fold their tabs; Journey folds the
+journal and the studio.
+
+### Guides
+
+A guide is one task, start to finish. It opens with the goal and a chip that says how long it is,
+**Quick**, **Guide** or **Walkthrough**, then:
+
+1. **Steps**, numbered. Each step is one sentence naming the app's own buttons and fields, with a
+   picture beside it. The picture is framed on the thing the sentence tells you to use, ringed in
+   your accent colour and numbered to match. A step that asks you to drag something shows both ends
+   and an arrow between them. Click a picture to open it full size.
+2. **What you get**, which says what changed, often with a picture of the result.
+3. **Good to know**, the caveats: what needs an addon, what cannot be undone, what a permission
+   hides.
+4. **Related**, the guides that go with this one, and **In the docs**, the wiki pages behind it.
+
+Some guides carry a button that takes you straight to the screen the task happens on.
+
+### Search
+
+The box at the top left searches **guides and the wiki at once**, from anywhere in the panel,
+including from inside a guide. Clearing it puts you back where you were.
+
+### The screen switcher
+
+**Screens** lists every screen that has help, so you can read about one screen while standing on
+another. Screens with sub-screens fold; the one you are actually on is marked **This screen**.
+
+## The pictures
+
+Every picture is generated by driving the real app: same viewport, same theme, same language, same
+demo trip, on every screen. Nothing is drawn, cropped or retouched by hand, and a picture only
+exists if the steps it shows still work. When a button moves or a label changes, the run that makes
+the pictures fails, which is how the guides stay honest.
+
+The pictures ship with your install as WebP and are loaded only when you open the panel, so they
+cost nothing to a visitor who never asks for help.
+
+## Languages
+
+The guides are written in English first and translated into every language TREK speaks. Every button
+and field a guide names is the app's own string in that language, so what you read matches what you
+see.
+
+## When a screen has no help yet
+
+The panel says so and leaves the search box as the way forward. Under it are the two places to ask a
+person: **Tell us on GitHub** opens a discussion, **Ask on Discord** opens the chat.
+
+## See also
+
+- [In-App Help](In-App-Help) - the wiki rendered inside TREK at `/help`
+- [Trip Planner Overview](Trip-Planner-Overview)
+- [FAQ](FAQ)
+- [Troubleshooting](Troubleshooting)

wiki/Home.md

@@ -62,6 +62,10 @@ TREK is a self-hosted, real-time collaborative travel planner licensed under AGP
 - **35 OAuth Scopes**: granular permissions across 17 permission groups
 - **Pre-built Prompts**: `trip-summary`, `packing-list`, and `budget-overview` context loaders
 
+### Help
+- **Help Center**: the `?` in the navbar opens guides for the screen you are on, with a picture of every step and search across guides and the wiki, in every language TREK speaks (see [Help Center](Help-Center))
+- **In-App Help**: the whole wiki, bundled with your install and read inside TREK at `/help` (see [In-App Help](In-App-Help))
+
 ### Admin
 - User management, invite links, packing templates, global categories
 - Addon management, API key storage, scheduled auto-backups
@@ -75,6 +79,7 @@ TREK is a self-hosted, real-time collaborative travel planner licensed under AGP
 |---|---|
 | [Quick Start](Quick-Start) | Install in minutes with a single Docker command |
 | [My Trips Dashboard](My-Trips-Dashboard) | Start planning your first trip |
+| [Help Center](Help-Center) | The `?` in the navbar: guides for the screen you are on |
 | [Admin Panel](Admin-Panel-Overview) | Configure your instance |
 | [MCP / AI Integration](MCP-Overview) | Connect Claude, Cursor, or any MCP client |
 | [Contributing](Contributing) | Guidelines for submitting pull requests |

wiki/In-App-Help.md

@@ -59,6 +59,7 @@ No permission gates the help browser; any signed-in user sees the same pages. Th
 
 ## See also
 
+- [Help Center](Help-Center) - the `?` panel, which is a different thing: guides for the screen you are on
 - [FAQ](FAQ)
 - [Troubleshooting](Troubleshooting)
 - [Environment-Variables](Environment-Variables)

wiki/_Sidebar.md

@@ -114,6 +114,7 @@
 - [[Security Hardening|Security-Hardening]]
 
 ## Help
+- [[Help Center|Help-Center]]
 - [[In-App Help|In-App-Help]]
 - [[FAQ]]
 - [[Troubleshooting]]