docs: name the memory cap on small hosts and the shared connection pool

Getting started names the APP_MEMORY_LIMIT default and how to lower it
on a 2 GB host; the scaling guide says that web and worker share one
pool in the bundled single-container setup. The rollup comment names
migration 0372, which carries the hourly-mean statistic.

docs/self-hosting/getting-started.md

@@ -13,7 +13,12 @@ already installed, longer if a TLS-fronted public hostname is in scope
     unchanged.
 - **2 GB RAM, 10 GB free disk.** The Postgres data volume grows with
   measurement history; the Apple Health import worker can briefly
-  hold a 1.5 GB upload in `/tmp` while it parses.
+  hold a 1.5 GB upload in `/tmp` while it parses. The app container is
+  capped at `APP_MEMORY_LIMIT`, `1536m` by default (Node then sizes its
+  heap at about 792 MB). On a 2 GB host that leaves too little for
+  Postgres and the system, so set `APP_MEMORY_LIMIT=1g` in `.env`
+  (a heap of about 524 MB); a long-used account then runs closer to
+  that heap, and the weekly backup with it.
 - **Outbound HTTPS** to `ghcr.io` (image pulls) plus whichever
   integration endpoints you plan to enable (Withings, OpenAI, etc.).
   The opt-in environmental-context module additionally reaches

docs/self-hosting/scaling.md

@@ -163,7 +163,11 @@ the knob as `DB_CONNECTION_LIMIT`, baked into `DATABASE_URL` as
 `connection_limit`; `DATABASE_POOL_MAX` remains a working explicit
 override. Resolution order: `DB_CONNECTION_LIMIT`, then
 `DATABASE_POOL_MAX`, then the `connection_limit` URL parameter, then
-the default of 20.
+the default of 20. In the bundled single-container setup
+(`HEALTHLOG_PROCESS_TYPE=all`) the web requests and the background
+worker run in one process and share that one Prisma pool, so a budget
+sized for the web traffic alone leaves the worker's jobs queueing for
+the same connections.
 
 Plan total Postgres slots as **container_count × budget**.
 A stock Postgres 16 container ships with `max_connections = 100`, so

src/lib/rollups/measurement-rollups.ts

@@ -597,7 +597,7 @@ async function runRollupAggregate(
  * every reading, so the band and the windowed slope are untouched.
  *
  * Hours and days are UTC, matching the UTC day this tier buckets by; migration
- * 0373 applies the same statistic to rows stored before it.
+ * 0372 applies the same statistic to rows stored before it.
  */
 async function applyHourlyMeanDay(
   db: Pick<typeof prisma, "$queryRawUnsafe">,