List every setting upaas reads in the README Configuration table (closes #229)

The table left out UPAAS_MAINTENANCE_MODE, UPAAS_SESSION_SECRET and
UPAAS_CORS_ORIGINS, and several rows gave the wrong default or effect.
Each row now matches internal/config/config.go and the code that uses
the value: UPAAS_PORT is also read and wins over PORT, UPAAS_DATA_DIR
must be absolute for deploys unless UPAAS_HOST_DATA_DIR is set,
UPAAS_HOST_DATA_DIR falls back to UPAAS_DATA_DIR and must be absolute
when set, UPAAS_DEBUG also drops the session cookie's Secure flag,
UPAAS_SENTRY_DSN is not used, and /metrics exists only when
UPAAS_METRICS_USERNAME is set. A sentence under the table names the
standard Docker client variables. TODO.md records the step.

Model: opus-5-5

README.md

@@ -237,11 +237,10 @@ HOST_DATA_DIR=/srv/upaas/data
 ```
 
 Other settings from [Configuration](#configuration) go in the same file, except
-`PORT`, `UPAAS_PORT` and `UPAAS_DATA_DIR`: the compose file sets both port
-settings to 8080 and `UPAAS_DATA_DIR` to `/var/lib/upaas`, overriding `.env`, to
-match its port mapping, healthcheck and data directory mount. Then run
-`docker compose up -d` from the repo root; `docker compose ps` shows the
-container as healthy once `/health` answers.
+`PORT` and `UPAAS_DATA_DIR`: the compose file sets them to 8080 and
+`/var/lib/upaas`, overriding `.env`, to match its port mapping, healthcheck and
+data directory mount. Then run `docker compose up -d` from the repo root;
+`docker compose ps` shows the container as healthy once `/health` answers.
 
 **Important**: `HOST_DATA_DIR` **must** be an **absolute path** on the host. It
 is bind-mounted into the container and passed as `UPAAS_HOST_DATA_DIR` so that

TODO.md

@@ -20,11 +20,6 @@ regress.
 
 # Completed Steps
 
-- 2026-09-29: `docker-compose.yml` now sets `UPAAS_PORT` to 8080 as well as
-  `PORT`, since upaas reads `UPAAS_PORT` first and a `UPAAS_PORT` in `.env` made
-  it listen away from the port mapping and healthcheck; the README's Compose
-  section names both (#230).
-
 - 2026-09-29: The README Configuration table now lists every setting upaas
   reads, adding `UPAAS_MAINTENANCE_MODE`, `UPAAS_SESSION_SECRET` and
   `UPAAS_CORS_ORIGINS`, and gives the real default and effect of each:

docker-compose.yml

@@ -7,11 +7,9 @@ services:
     # Every line of .env is passed to upaas as an environment variable.
     env_file: .env
     environment:
-      # Override any PORT or UPAAS_PORT in .env, so upaas listens where the
-      # port mapping and healthcheck below expect it. Both are set because
-      # upaas reads UPAAS_PORT first.
+      # Overrides any PORT in .env, so upaas listens where the port mapping
+      # and healthcheck below expect it.
       PORT: "8080"
-      UPAAS_PORT: "8080"
       # Overrides any UPAAS_DATA_DIR in .env, so the database stays on the
       # HOST_DATA_DIR mount below instead of inside the container.
       UPAAS_DATA_DIR: /var/lib/upaas