docs(user): add user_docs/ end-user guide (12 pages)

A friendly, task-oriented guide for non-technical users: README index,
getting-started, concepts, items, passwords-and-generators, totp,
attachments-and-documents, organizing, sync-and-backup, the-browser-extension,
recovery, faq. Every command/flag derived from the actual CLI surface
(`relicario --help` tree) and real extension behavior — no invented flags.
Org item-type parity is covered high-level pending the v0.8.1 B/C merge
(two TODO markers left for the rebase).

user_docs/README.md

@@ -0,0 +1,51 @@
+# Relicario — User Guide
+
+Welcome! Relicario is a password manager that keeps your logins, cards, notes, and files
+safe — and keeps **you** in control of where they live. This guide is for everyday users:
+no programming or cryptography knowledge required.
+
+> **The one-minute version.** Your vault lives in a git repository *you* control (your own
+> Gitea or GitHub). The server only ever sees scrambled, unreadable data. To unlock your
+> vault you need **two things together**: a **passphrase** you remember, and a **reference
+> photo** (an ordinary JPEG you chose, with a secret hidden inside it). Neither one alone can
+> open the vault — that's what keeps your secrets yours.
+
+## Start here
+
+New to Relicario? Read these first, in order:
+
+1. **[Getting started](getting-started.md)** — install it, create your first vault, and add your first login (about 10 minutes).
+2. **[How Relicario works](concepts.md)** — the two-factor idea, where your data is stored, and the one golden rule.
+3. **[Items](items.md)** — the seven kinds of things you can store, and how to add, view, edit, and delete them.
+
+## Everyday tasks
+
+- **[Passwords & generators](passwords-and-generators.md)** — create strong passwords and passphrases, and check how strong they are.
+- **[Two-factor codes (TOTP)](totp.md)** — store the rotating 6-digit codes for sites that use authenticator apps.
+- **[Attachments & documents](attachments-and-documents.md)** — keep files and scanned documents in your vault.
+- **[Organizing your vault](organizing.md)** — groups, tags, favorites, and search.
+- **[Sync & backup](sync-and-backup.md)** — use your vault on more than one computer, and back it up safely.
+- **[The browser extension](the-browser-extension.md)** — unlock, search, and autofill logins right in Chrome or Firefox.
+
+## Before you need it
+
+- **[Recovery — and its limits](recovery.md)** — how to protect against losing access, and the honest truth about what *cannot* be recovered. **Please read this one early, not after something goes wrong.**
+- **[FAQ](faq.md)** — quick answers to common questions.
+
+## For the technically curious
+
+This guide deliberately skips the engineering details. If you want to understand how the
+encryption, the hidden-image secret, or the data formats actually work, see the technical
+documentation in the repository:
+
+- [`../DESIGN.md`](../DESIGN.md) — the big picture across all the pieces.
+- [`../docs/CRYPTO.md`](../docs/CRYPTO.md) — how the two factors become a key, and how data is encrypted.
+- [`../docs/SECURITY.md`](../docs/SECURITY.md) — the threat model: what Relicario protects against, and what it doesn't.
+- [`../docs/FORMATS.md`](../docs/FORMATS.md) — the on-disk and wire formats.
+
+Relicario is free and open source under the GPL-3.0-or-later license — you're welcome to read,
+build, and verify every line.
+
+---
+
+**Next:** [Getting started](getting-started.md)