feat: smart wiki filenames — sanitize special characters to hyphens

New wiki page titles are now sanitized before creating the git file:
- Spaces and special characters replaced with hyphens
- Consecutive hyphens collapsed to single hyphen
- Leading/trailing hyphens trimmed

Examples:
- "My Page Name" -> "My-Page-Name"
- "API & Docs (v2)" -> "API-Docs-v2"
- "100% Complete!!" -> "100-Complete"

Only affects NEW pages. Existing wiki pages with legacy filenames
(spaces, URL encoding) continue to work — the read path is unchanged.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

services/wiki/wiki_path.go

@@ -6,6 +6,7 @@ package wiki
 import (
 	"net/url"
 	"path"
+	"regexp"
 	"strings"
 
 	repo_model "git.mokoconsulting.tech/MokoConsulting/MokoGitea/models/repo"
@@ -148,10 +149,24 @@ func WebPathFromRequest(s string) WebPath {
 	return WebPath(s)
 }
 
+var multiHyphenRe = regexp.MustCompile(`-{2,}`)
+var nonAlphanumRe = regexp.MustCompile(`[^a-zA-Z0-9\-]`)
+
+// sanitizeWikiTitle converts a user-provided title into a clean, URL-friendly slug.
+// Spaces and special characters become hyphens, consecutive hyphens collapse to one.
+func sanitizeWikiTitle(title string) string {
+	title = strings.TrimSpace(title)
+	title = strings.ReplaceAll(title, " ", "-")
+	title = nonAlphanumRe.ReplaceAllString(title, "-")
+	title = multiHyphenRe.ReplaceAllString(title, "-")
+	title = strings.Trim(title, "-")
+	return title
+}
+
 func UserTitleToWebPath(base, title string) WebPath {
 	// TODO: no support for subdirectory, because the old wiki code's behavior is always using %2F, instead of subdirectory.
 	// So we do not add the support for writing slashes in title at the moment.
-	title = strings.TrimSpace(title)
+	title = sanitizeWikiTitle(title)
 	title = util.PathJoinRelX(base, escapeSegToWeb(title, false))
 	if title == "" || title == "." {
 		title = "unnamed"