Adds Bridges/MailTracy/MailPanel that subscribes to Interceptor::$onSent
and shows From / To+Cc+Bcc / Subject / Status of each sent message in
the Tracy Bar.

Wraps any Mailer with two debugging/safety features:
- optional redirect of To/Cc/Bcc and read-receipt headers
(Disposition-Notification-To, X-Confirm-Reading-To) to a fixed
email; originals preserved in X-Original-* headers; optional
subject prefix
- $onSent event fired after each send (success or failure), for
audit logs, metrics, or custom observers

The DI extension exposes 'mail.redirect' configuration that wires
the Interceptor automatically when the redirect address is set.

- new class composing HTML body for a Message: optional CSS inlining (via CssInliner), local image embedding, <title> -> subject extraction, plain-text alternative generation
- inlineCss() opt-in (no-arg inlines <style> tags, accumulates across calls)
- embedImages() opt-in, requires base path
- text generation and subject extraction always run (respect already-set values)
- Message::setHtmlBody() preserved as BC alias delegating to HtmlComposer
- Message::buildText() removed (logic moved to HtmlComposer::htmlToText)
- new internal Message::setRawHtmlBody() used by HtmlComposer to avoid recursion

* opened 3.0-dev

* requires PHP 8.1

* uses PascalCase constants

* removed bridge for Latte

* Logger: added typehints

* Logger: md5 replaced with xxHash

* error.log changed to warning.log

* bar: errors panel => warnings

* readme: added link to Joomla integration (#583)

Link to Joomla! integration.

* used attribute Deprecated

* Update readme.md

Add link to Yii3 integration

---------

Co-authored-by: David Grudl <david@grudl.com>
Co-authored-by: n3t <n3t@n3t.cz>

PHP 8.5 fixed stream_select() to work with proc_open() pipes on Windows
(PeekNamedPipe fix), so the temporary-file workaround for non-blocking
reads is no longer needed there - anonymous pipes are read in chunks
guarded by stream_select(). The temp-file fallback is kept for Windows
< 8.5.