✨ Add EmailLayout layout component

[damienlagae]

Summary

• Adds an EmailLayout component that replaces the abandoned @EnabelLayout/emails/base.html.twig from enabel/layout-bundle
• Table-based, inline styles, 600px centered — the only layout every email client renders reliably (Outlook, Gmail, Apple Mail, etc.)
• Renders the logo via Symfony Mailer's email.image() helper (CID-embedded inline)
• Exposes a {% block content %} block for the email body
• Configurable footer: address, no-reply notice (nullable), copyright year + holder

API

All optional with sensible defaults. Logo defaults to @images/enabel-logo-email.png (consumer registers the Twig namespace and ships the asset). copyrightYear resolves to date('Y') when omitted.

Test plan

• PHPUnit: 216/216 (11 new tests: defaults, custom params, copyrightYear resolution, nullable logo/noreply, invalid types)
• php-cs-fixer: clean
• phpstan: no errors
• Manual smoke test in a consumer app (Impala) — welcome / password-reset / text-only variants sent to Mailpit, HTML score 92-94%

Closes #17.

[damienlagae]

Smoke-tested in Impala (consumer app) — symlinked the branch via composer path repo, sent 3 emails through Symfony Mailer to Mailpit.

What I verified

Variant	Setup	Result
welcome	All defaults	Logo CID-embedded, 600px white card, footer + no-reply notice + © 2026 Enabel. Mailpit HTML-check 93%
password reset	noreply overridden (FR), copyrightHolder: 'Impala'	Both overrides applied, © 2026 Impala. 92%
text-only	logo: null, noreply: null, copyrightHolder: 'Impala'	Header block hidden entirely, no-reply line dropped. 94%

• email.image('@images/enabel-logo-email.png') correctly attaches the logo as inline CID (visible in Mailpit's "Inline image" indicator + bottom attachment panel)
• copyrightYear resolves to current year via date('Y') when omitted
• The {% component %} … {% block content %} … {% endcomponent %} pattern from the docs works as advertised; <tr><td> inside the block plugs into the outer table cleanly

Minor doc nitpick (optional)

The docs say to register '%kernel.project_dir%/public/images': images. In Impala this was already set up for unrelated reasons, but a new consumer pulling in only this component might miss it and hit a Unable to find template "@images/..." error from email.image(). The "Pre-requisite" section already mentions this — maybe just add an explicit note that the consumer must ship enabel-logo-email.png in public/images/ (the bundle doesn't carry the asset).

LGTM, ready to tag.