fix: keep trailing hyphens and dots in normalized feature names

Trimming them changed identifiers like "TEST-", which were valid and
unchanged before, breaking the promise that existing instances stay
reachable. Reject empty and relative path segments explicitly instead,
which is what the trim was actually guarding against.

Author: konradmichalik

docs/FEATURE.md

@@ -66,6 +66,10 @@ The `--feature=` value may be a full branch name. Path separators are replaced b
 
 Names that already consist of letters, digits, `_`, `-` and `.` are used unchanged, so existing instances and their databases stay reachable. Since the branch prefix is kept, `feature/TEST-01` and `bugfix/TEST-01` remain two separate instances. The same normalization is applied by `feature:cleanup` when it compares remote git branches with the deployed instances.
 
+A `--feature=` value that yields no usable name is rejected instead of falling back to the base instance, which the feature scaffolding would otherwise overwrite. That covers values without any allowed character as well as `.` and `..`.
+
+> Because the separator is replaced rather than encoded, `feature/TEST-01` and a branch literally named `feature-TEST-01` map to the same instance. Do not use both spellings for different branches in one project.
+
 The recipe already wires this task into the deploy flow, together with a `feature:init` before `deploy:info`. That ordering matters: `deploy:info` resolves `{{release_name}}` and deployer caches the result for the rest of the run, so the feature instance has to be known before it runs. Do not hook `feature:setup` any earlier yourself.
 
 > Upgrading: if your `deploy.php` carries a `before('deploy:info', 'feature:init')` (or an equivalent `feature:setup` hook) as a workaround for that ordering, remove it — the recipe registers it now and the hook would otherwise run twice.

src/Utility/FeatureUtility.php

@@ -19,7 +19,8 @@ final class FeatureUtility
      * databases reachable.
      *
      * @throws \InvalidArgumentException if a non-blank identifier normalizes to an empty
-     *                                   name, which would silently address the base instance
+     *                                   name or to a relative path segment, either of which
+     *                                   would silently address the base instance
      */
     public static function normalize(?string $feature): string
     {
@@ -31,11 +32,11 @@ public static function normalize(?string $feature): string
 
         $normalized = str_replace(['/', '\\'], '-', $feature);
         $normalized = (string) preg_replace('/[^A-Za-z0-9_\-.]/', '', $normalized);
-        $normalized = trim($normalized, '-.');
 
-        if ('' === $normalized) {
+        // "" would resolve to the base instance, "." and ".." to it or its parent
+        if ('' === trim($normalized, '.')) {
             throw new \InvalidArgumentException(
-                sprintf('The feature name "%s" contains no usable characters.', $feature)
+                sprintf('The feature name "%s" does not yield a usable instance name.', $feature)
             );
         }