P5: OSS readiness — docs site, contributor onboarding, e2e harness

P5-01 — Documentation site under docs/book/ rendered with mdBook
(downloaded via Makefile, same static-binary pattern as Tailwind).
Structured chapters: getting started, concepts, operations,
security, reference. `make docs` / `make docs-watch`. Generated
output gitignored.

P5-02 — CONTRIBUTING.md rewritten from placeholder to a full
guide. CODE_OF_CONDUCT.md adapted from Contributor Covenant for a
single-maintainer project. .gitea/issue_template/{bug,feature}.md
and PULL_REQUEST_TEMPLATE.md.

P5-04 — Six README screenshots captured live from a fresh server
bootstrap (login, empty dashboard, add-host, alerts, settings,
audit log). README rewritten to centre the screenshot grid and
link out to the docs site.

P5-05 — SECURITY.md with disclosure policy (3-day ack, 30-day
default window), scope in/out, threat-model summary, operator
hardening checklist. Mirrored as a docs-site chapter.

P5-06 — End-to-end test harness. e2e/compose.e2e.yml brings up
server + sibling Linux agent (alpine + restic) + restic/rest-server.
Agent uses announce-and-approve so Playwright can drive the full
operator flow: bootstrap → login → accept pending → backup →
verify terminal status. Second spec scrapes /metrics to assert
the P6-04 endpoint surface. .gitea/workflows/e2e.yml runs on every
PR; local how-to in docs/e2e.md.

CODE_OF_CONDUCT.md

@@ -0,0 +1,69 @@
+# Code of Conduct
+
+restic-manager is a small project run by one person. This Code of
+Conduct sets out the basic expectations for participating in the
+project's issue tracker, pull requests, and any other community
+spaces (chat, mailing lists) we may run in future.
+
+## Expected behaviour
+
+- **Be civil.** Disagreement is fine; rudeness is not. The same
+  comment can usually be made without making it personal.
+- **Assume good faith.** People asking what feels like a basic
+  question may be new to the project. People proposing what feels
+  like a duplicate idea may not have seen the prior discussion.
+  Point them to the right place politely.
+- **Stay on topic.** Issue threads are for the issue. Tangential
+  conversations belong in their own thread.
+- **Acknowledge the project's scope.** restic-manager is
+  intentionally small in scope (see `spec.md` §2). Reasonable
+  feature suggestions may still be declined for fit reasons.
+
+## Unacceptable behaviour
+
+- Harassment, threats, or insults — public or private.
+- Discriminatory comments based on age, body size, disability,
+  ethnicity, gender identity or expression, level of experience,
+  nationality, personal appearance, race, religion, sexual identity
+  or orientation.
+- Sustained disruption — derailing threads, ignoring repeated
+  requests to take a discussion elsewhere, brigading.
+- Publishing other people's private information without permission.
+
+## Reporting
+
+If someone in the project's spaces is behaving in a way that
+breaches this Code of Conduct, contact the maintainer directly
+through the contact details on their Gitea profile, or via the
+private security disclosure path documented in
+[SECURITY.md](./SECURITY.md). Reports stay confidential.
+
+The maintainer will review the report, gather context if needed,
+and respond. Possible outcomes include a private warning, a public
+clarification of expectations, a temporary or permanent ban from
+project spaces, or no action if the report doesn't hold up.
+
+There is no formal appeals process — this is a one-person project,
+not a foundation. If you think a decision was wrong you can say
+so, in writing, to the maintainer; that's it.
+
+## Scope
+
+This Code of Conduct applies to interactions in any space the
+project owns or operates: the Gitea repository (issues, pull
+requests, discussions, wiki), any chat channels we publish, and
+any conferences or events the project is officially represented at.
+
+It does not apply to:
+
+- Forks of the project that aren't being submitted back upstream.
+- Conversations between contributors that don't reference the
+  project.
+- Public criticism of the project itself.
+
+## Acknowledgement
+
+This document borrows shape and language from the
+[Contributor Covenant](https://www.contributor-covenant.org/) v2.1
+but is intentionally shorter and adapted to the project's
+single-maintainer reality.