build: M1 Dockerized development stack with PHP skeleton, config/logging, Tailwind assets, and wrappers

Implements MeshVault M1 (issues #6–11):

- Four-service Docker Compose stack (nginx, PHP-FPM 8.3, PostgreSQL 17, Node assets)
- Slim 4 + PHP-DI routing with escaped PHP views and production/dev error handling
- Immutable validated AppConfig with redacted diagnostics
- JSON stdout Monolog logging with job-scoped context
- Tailwind CSS v4 deterministic locked builds with template scanning
- POSIX and PowerShell dev wrappers (up/down/test/lint/assets/watch)
- Startup config validation fails before FPM serves as unprivileged www-data
- migrate/seed explicitly unavailable until M2 (#12); #10 remains open

Verified via clean-start acceptance on remote host (keith@192.168.2.23).

phpunit.xml.dist

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/12.5/phpunit.xsd"
+         bootstrap="vendor/autoload.php" cacheDirectory=".phpunit.cache"
+         failOnWarning="true" failOnRisky="true" failOnNotice="true" failOnDeprecation="true">
+    <testsuites>
+        <testsuite name="unit"><directory>tests/Unit</directory></testsuite>
+        <testsuite name="http"><directory>tests/Http</directory></testsuite>
+        <testsuite name="integration"><directory>tests/Integration</directory></testsuite>
+    </testsuites>
+</phpunit>