feat: public rate-limited access for v1.1

Add PublicAccessListener (priority 84) that allows rate-limited
unauthenticated access to configured public paths. Authenticated users
bypass this listener entirely via AcceptListener/AllowListener.

New components:
- PublicPathMatcher service with wildcard path matching (* and **)
  and optional host-prefix scoping
- PublicAccessListener applying per-IP rate limiting to public paths
- Separate public_limiter compound rate limiter (burst + sustained)
- publicRateLimitCache pool (APCu in prod, array in tests)

New env vars:
- PUBLIC_PATHS (comma-separated path patterns, empty = disabled)
- PUBLIC_BURST_COUNT/PUBLIC_BURST_TIME (default 100/60s)
- PUBLIC_UPPER_COUNT/PUBLIC_UPPER_TIME (default 500/3600s)

Tests: 52 new tests (29 unit for PublicPathMatcher, 12 unit for
PublicAccessListener, 11 functional for PublicAccessFlowTest).
Total: 293 tests, 605 assertions, all passing.
PHP CS Fixer: 0 of 63 files need fixing.

Documentation: README, CHANGELOG, ROADMAP, Caddyfile, example.env
all updated with public access configuration and examples.

src/Service/PublicPathMatcherInterface.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service;
+
+/**
+ * Matches request paths against configured public path patterns.
+ *
+ * Patterns support simple wildcards:
+ *  - `*`  matches any characters within a single path segment (not crossing `/`)
+ *  - `**` matches any characters including `/` (crosses path segments)
+ *
+ * Patterns may optionally include a host prefix (e.g. `example.com/public/**`).
+ * When no host prefix is given, the pattern matches on any host.
+ */
+interface PublicPathMatcherInterface
+{
+    /**
+     * Returns true if the given host and path match any configured public pattern.
+     *
+     * @param string $host The request host (e.g. "code.example.com")
+     * @param string $path The request path (e.g. "/public/repo/issues")
+     */
+    public function matches(string $host, string $path): bool;
+
+    /**
+     * Returns true if no public paths are configured (feature is disabled).
+     */
+    public function isEmpty(): bool;
+}