Close out issue 001: document CSRF/reverse-proxy requirement

The app-side fix (CSRF_TRUSTED_ORIGINS, SECURE_PROXY_SSL_HEADER in
settings.py) was already committed as d458cd3 after the first Cloud-VM-1
deployment hit "CSRF verification failed" on login behind Apache. This
finishes the rest of that issue's checklist: documents
DJANGO_CSRF_TRUSTED_ORIGINS in deploy/env.example, adds the required
X-Forwarded-Proto header to the Apache/Caddy examples in
cloud_agent_deploy.md (plus a checklist item that verifies via an actual
login, not just an unauthenticated capabilities curl), and adds the same
proxy-agnostic guidance to docs/deployment.md.

Also introduces issues/, a tracked one-file-per-issue log for the project
going forward.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

issues/001-csrf-behind-reverse-proxy.md

@@ -0,0 +1,71 @@
+# 001 — CSRF verification fails behind a TLS-terminating reverse proxy
+
+**Status:** Fixed
+
+## Description
+
+Deploying Daybook behind Apache (TLS-terminating reverse proxy → plain HTTP
+to the container) on `cloud-vm-1`, login failed with:
+
+```
+Forbidden (403)
+CSRF verification failed. Request aborted.
+```
+
+**Root cause:** `daybook_project/settings.py` set `ALLOWED_HOSTS` from an env
+var but never set `CSRF_TRUSTED_ORIGINS` or `SECURE_PROXY_SSL_HEADER`. Without
+the latter, Django has no way to know the original request was HTTPS — the
+proxy terminates TLS and forwards plain HTTP — so it treats every request as
+insecure, which breaks CSRF checks on any POST (including login) once a
+browser connects over `https://`.
+
+This isn't specific to `cloud-vm-1` — it'll happen on any reverse-proxied
+deployment (Apache, Nginx, Traefik, a cloud load balancer), which is the
+explicitly recommended setup in `deploy/cloud_agent_deploy.md` §8. The
+runbook doesn't mention CSRF or proxy-awareness anywhere.
+
+## Fix
+
+**App (`daybook_project/settings.py`):**
+
+```python
+CSRF_TRUSTED_ORIGINS = [origin.strip() for origin in os.environ.get("DJANGO_CSRF_TRUSTED_ORIGINS", "").split(",") if origin.strip()]
+SECURE_PROXY_SSL_HEADER = ("HTTP_X_FORWARDED_PROTO", "https")
+```
+
+Committed locally as `d458cd3` ("Fix CSRF failure behind a TLS-terminating
+reverse proxy") — **needs to be pushed to `main`**, the deploy agent that
+made this fix didn't have push access to the Forgejo repo.
+
+**Deploy env (`deploy/env.example` / runbook):** needs a new var,
+`DJANGO_CSRF_TRUSTED_ORIGINS`, set to the public HTTPS origin, e.g.:
+
+```
+DJANGO_CSRF_TRUSTED_ORIGINS=https://daybook.example.com
+```
+
+**Proxy config:** `SECURE_PROXY_SSL_HEADER` only works if the proxy actually
+sends that header. The Apache example in `cloud_agent_deploy.md` §8 is
+missing it — needs:
+
+```apache
+RequestHeader set X-Forwarded-Proto "https"
+```
+
+inside the `<VirtualHost *:443>` block (requires `a2enmod headers`). The
+equivalent for Nginx is `proxy_set_header X-Forwarded-Proto $scheme;`, worth
+adding to `docs/deployment.md`'s reverse-proxy notes too since that doc
+mentions Nginx/Traefik as options without this caveat.
+
+## Resolution
+
+- [x] Pushed commit `d458cd3` to `main`.
+- [x] Added `DJANGO_CSRF_TRUSTED_ORIGINS` to `deploy/env.example` with an
+      explanatory comment.
+- [x] Updated `cloud_agent_deploy.md` §8's Apache example to include
+      `RequestHeader set X-Forwarded-Proto "https"`, plus a Caddy equivalent
+      and a checklist item that verifies by actually logging in through the
+      proxy (not just curling `/api/capabilities`, which is unauthenticated
+      GET and wouldn't have caught this).
+- [x] Updated `docs/deployment.md`'s "Reverse Proxy Notes" and checklist with
+      the same requirement, plus an Nginx/Apache/Caddy header cheat sheet.

issues/README.md

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+# Issues
+
+One file per issue: `NNN-short-slug.md`, numbered sequentially. Each file
+has a title, status (Open / Fixed / By design), description, and resolution
+once closed.