Add PlanetScale configuration details to keynote README & DEVELOP (#4474)

# Description of Changes

- **keynote-2 docs:** Document PlanetScale benchmark configuration in
DEVELOP.md (env vars `PLANETSCALE_PG_URL`, `PLANETSCALE_RPC_URL`,
`SKIP_PLANETSCALE_PG`; short “create DB and set env” section; note that
we benchmarked using PS-2560, 32 vCPUs, 256 GB RAM).
- **README:** Add PlanetScale to cloud tier list (PS-2560, single node,
us-central1). Add region (us-central1) to Hardware Configuration for
Server Machine Variant B and Client Machine.

No code or config changes; documentation only.

# API and ABI breaking changes

None.

# Expected complexity level and risk

**Complexity: 1.** Doc-only updates to `templates/keynote-2/README.md`
and `templates/keynote-2/DEVELOP.md`. No behavioral or API impact.

# Testing

- [ ] Skim README and DEVELOP.md for accuracy and formatting.

Author: bradleyshep

templates/keynote-2/DEVELOP.md

@@ -102,6 +102,12 @@ Copy `.env.example` to `.env` and adjust.
 - `CLEAR_CONVEX_ON_PREP` – Convex prep flag (clears data when enabled)
 - `CONVEX_USE_SHARDED_COUNTER` – flag for using the sharded-counter implementation
 
+**PlanetScale:**
+
+- `PLANETSCALE_PG_URL` – Postgres connection string
+- `PLANETSCALE_RPC_URL` – PlanetScale RPC server URL (default: `http://127.0.0.1:4104`)
+- `SKIP_PLANETSCALE_PG` – `1` = skip PlanetScale in prep
+
 **Bun / RPC helpers:**
 
 - `BUN_URL` – Bun HTTP benchmark server URL
@@ -115,6 +121,12 @@ Copy `.env.example` to `.env` and adjust.
 
 ---
 
+## PlanetScale configuration
+
+Create a Postgres database on PlanetScale and set `PLANETSCALE_PG_URL` (and `PLANETSCALE_RPC_URL` if the RPC server runs elsewhere) in `.env`. Reported results used PS-2560 (32 vCPUs, 256 GB RAM).
+
+---
+
 ## Setup
 
 ### Generate bindings (first time after clone)

templates/keynote-2/README.md

@@ -48,7 +48,7 @@ All systems were tested with **out-of-the-box default settings** - no custom tun
 
 For cloud services, we tested paid tiers to give them their best chance:
 
-- **PlanetScale**: PS-256G (32 cores, 256 GB RAM)
+- **PlanetScale**: PS-2560 (32 vCPUs, 256 GB RAM), single node, us-central1.
 - **Supabase**: Pro tier
 - **Convex**: Pro tier
 
@@ -101,10 +101,12 @@ docker compose run --rm bench --seconds 10 --concurrency 50 --alpha XX --connect
 
 - c4-standard-32-lssd (32 vCPUs, 120 GB Memory) OS: Ubuntu 24.04
 - RAID 0 on 5 Local SSDs
+- Region: us-central1
 
 **Client Machine:**
 
 - c4-standard-32 (32 vCPUs, 120 GB Memory) OS: Ubuntu 24.04
+- Region: us-central1
 - Runs on a **separate machine** from the server
 
 **Note:** All services (databases, web servers, benchmark runner) except Convex local dev backend run in the same Docker environment on the server machine.