chore: auto-commit (57 archivos)

- frontend/functions/core/format_datetime_short.md
- frontend/functions/core/format_datetime_short.test.ts
- frontend/functions/core/format_datetime_short.ts
- frontend/functions/core/format_duration.md
- frontend/functions/core/format_duration.test.ts
- frontend/functions/core/format_duration.ts
- frontend/functions/core/month_grid.md
- frontend/functions/core/month_grid.test.ts
- frontend/functions/core/month_grid.ts
- frontend/functions/core/string_hash_palette.md
- ...

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

functions/infra/http_session_cookie_set.go

@@ -0,0 +1,21 @@
+package infra
+
+import (
+	"net/http"
+	"time"
+)
+
+// SessionCookieSet writes a session cookie to the response.
+// The cookie is HttpOnly, Path="/", SameSite=Lax and expires at the
+// Unix timestamp expiresAt (seconds). It does not return an error
+// because http.SetCookie never fails at runtime.
+func SessionCookieSet(w http.ResponseWriter, name, token string, expiresAt int64) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     name,
+		Value:    token,
+		Path:     "/",
+		HttpOnly: true,
+		SameSite: http.SameSiteLaxMode,
+		Expires:  time.Unix(expiresAt, 0),
+	})
+}