feat: upgrade PostgreSQL 16 → 18 & fix devcontainer zombie processes (#381)

* fix: suppress act() warnings and unhandled rejections in tests

Configure testing-library for React 18+ and suppress harmless act()
warnings that occur due to async state updates completing after test cleanup.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* feat: upgrade postgresql from 16 to 18

Upgrade devcontainer database to PostgreSQL 18.1 (released Sept 2025).

Key benefits:
- 3x performance with new Async I/O subsystem
- UUIDv7 function for timestamp-ordered UUIDs
- Virtual generated columns
- Skip scan on multicolumn B-tree indexes
- OAuth 2.0 authentication support

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix: add init to devcontainer to prevent zombie processes

Adds `init: true` to the devcontainer service which uses tini as PID 1.
This properly reaps zombie processes that accumulate from DevPod sessions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* docs: add container naming convention for devpod

Adds instructions for configuring username-based container names
when multiple developers share the same remote server.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Mohsin Hashmi <mhashmi@wiser.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: 3 people

.devcontainer/docker-compose.yml

@@ -5,6 +5,7 @@ services:
   devcontainer:
     image: ghcr.io/simpleaccounts/simpleaccounts-uae-devcontainer:latest
     # Note: Add .env file in .devcontainer/ for custom environment variables
+    init: true # Use tini as PID 1 to properly reap zombie processes
 
     volumes:
       - ../:/workspaces/SimpleAccounts-UAE:cached

docs/DEVPOD_SETUP.md

@@ -279,6 +279,40 @@ devpod provider add ssh --option HOST=dev-server
 devpod up https://github.com/SimpleAccounts/SimpleAccounts-UAE --provider ssh --ide vscode
 ```
 
+## Container Naming Convention
+
+When multiple developers use the same remote server, container names can be confusing. By default, DevPod generates random names like `simpleacco-d415b` or `default-mu-f2154`.
+
+### Configure Username in Container Names
+
+To include your username in container names for easier identification:
+
+**Option 1: Set per-workspace (recommended)**
+
+```bash
+COMPOSE_PROJECT_NAME="${USER}-simpleaccounts" devpod up https://github.com/SimpleAccounts/SimpleAccounts-UAE --ide vscode
+```
+
+**Option 2: Set globally for SSH provider**
+
+```bash
+devpod provider set-options ssh DOCKER_COMPOSE_PROJECT_NAME='${USER}-simpleaccounts'
+```
+
+**Option 3: Create a shell alias**
+
+Add to your `~/.bashrc` or `~/.zshrc`:
+
+```bash
+alias devpod-sa='COMPOSE_PROJECT_NAME="${USER}-simpleaccounts" devpod up https://github.com/SimpleAccounts/SimpleAccounts-UAE'
+
+# Usage:
+devpod-sa --ide vscode
+devpod-sa --ide cursor
+```
+
+This will create containers named like `john-simpleaccounts-devcontainer-1` instead of `default-abc123-devcontainer-1`.
+
 ## Resources
 
 - [DevPod Documentation](https://devpod.sh/docs)